diff --git a/src/backend.rs b/src/backend/mod.rs
similarity index 59%
rename from src/backend.rs
rename to src/backend/mod.rs
index ae86be2..fd0b60d 100644
--- a/src/backend.rs
+++ b/src/backend/mod.rs
@@ -1,31 +1,27 @@
-use crate::{backend_opt::UpstreamOption, log::*};
-use rand::Rng;
-use rustc_hash::{FxHashMap as HashMap, FxHashSet as HashSet};
+mod upstream;
+mod upstream_opts;
+
+use crate::log::*;
+use rustc_hash::FxHashMap as HashMap;
 use std::{
-  borrow::Cow,
   fs::File,
   io::{self, BufReader, Cursor, Read},
   path::PathBuf,
-  sync::{
-    atomic::{AtomicUsize, Ordering},
-    Arc,
-  },
+  sync::Arc,
 };
 use tokio_rustls::rustls::{
   server::ResolvesServerCertUsingSni,
   sign::{any_supported_type, CertifiedKey},
   Certificate, PrivateKey, ServerConfig,
 };
+pub use upstream::{ReverseProxy, Upstream, UpstreamGroup};
+pub use upstream_opts::UpstreamOption;
 
-// server name (hostname or ip address) in ascii lower case
-pub type ServerNameLC = Vec<u8>;
-pub type PathNameLC = Vec<u8>;
-
-pub struct Backends {
-  pub apps: HashMap<ServerNameLC, Backend>, // hyper::uriで抜いたhostで引っ掛ける
-  pub default_server_name: Option<ServerNameLC>, // for plaintext http
-}
+// server name (hostname or ip address) and path name representation in backends
+pub type ServerNameExp = Vec<u8>; // lowercase ascii bytes
+pub type PathNameExp = Vec<u8>; // lowercase ascii bytes
 
+/// Struct serving information to route incoming connections, like server name to be handled and tls certs/keys settings.
 pub struct Backend {
   pub app_name: String,
   pub server_name: String,
@@ -37,104 +33,6 @@ pub struct Backend {
   pub https_redirection: Option<bool>,
 }
 
-#[derive(Debug, Clone)]
-pub struct ReverseProxy {
-  pub upstream: HashMap<PathNameLC, UpstreamGroup>, // TODO: HashMapでいいのかは疑問。max_by_keyでlongest prefix matchしてるのも無駄っぽいが。。。
-}
-
-impl ReverseProxy {
-  pub fn get<'a>(&self, path_str: impl Into<Cow<'a, str>>) -> Option<&UpstreamGroup> {
-    // trie使ってlongest prefix match させてもいいけどルート記述は少ないと思われるので、
-    // コスト的にこの程度で十分
-    let path_lc = path_str.into().to_ascii_lowercase();
-    let path_bytes = path_lc.as_bytes();
-
-    let matched_upstream = self
-      .upstream
-      .iter()
-      .filter(|(route_bytes, _)| {
-        match path_bytes.starts_with(route_bytes) {
-          true => {
-            route_bytes.len() == 1 // route = '/', i.e., default
-            || match path_bytes.get(route_bytes.len()) {
-              None => true, // exact case
-              Some(p) => p == &b'/', // sub-path case
-            }
-          }
-          _ => false,
-        }
-      })
-      .max_by_key(|(route_bytes, _)| route_bytes.len());
-    if let Some((_path, u)) = matched_upstream {
-      debug!(
-        "Found upstream: {:?}",
-        String::from_utf8(_path.to_vec()).unwrap_or_else(|_| "<none>".to_string())
-      );
-      Some(u)
-    } else {
-      None
-    }
-  }
-}
-
-#[allow(dead_code)]
-#[derive(Debug, Clone)]
-pub enum LoadBalance {
-  RoundRobin,
-  Random,
-}
-impl Default for LoadBalance {
-  fn default() -> Self {
-    Self::RoundRobin
-  }
-}
-
-#[derive(Debug, Clone)]
-pub struct Upstream {
-  pub uri: hyper::Uri, // base uri without specific path
-}
-
-#[derive(Debug, Clone)]
-pub struct UpstreamGroup {
-  pub upstream: Vec<Upstream>,
-  pub path: PathNameLC,
-  pub replace_path: Option<PathNameLC>,
-  pub lb: LoadBalance,
-  pub cnt: UpstreamCount, // counter for load balancing
-  pub opts: HashSet<UpstreamOption>,
-}
-
-#[derive(Debug, Clone, Default)]
-pub struct UpstreamCount(Arc<AtomicUsize>);
-
-impl UpstreamGroup {
-  pub fn get(&self) -> Option<&Upstream> {
-    match self.lb {
-      LoadBalance::RoundRobin => {
-        let idx = self.increment_cnt();
-        self.upstream.get(idx)
-      }
-      LoadBalance::Random => {
-        let mut rng = rand::thread_rng();
-        let max = self.upstream.len() - 1;
-        self.upstream.get(rng.gen_range(0..max))
-      }
-    }
-  }
-
-  fn current_cnt(&self) -> usize {
-    self.cnt.0.load(Ordering::Relaxed)
-  }
-
-  fn increment_cnt(&self) -> usize {
-    if self.current_cnt() < self.upstream.len() - 1 {
-      self.cnt.0.fetch_add(1, Ordering::Relaxed)
-    } else {
-      self.cnt.0.fetch_and(0, Ordering::Relaxed)
-    }
-  }
-}
-
 impl Backend {
   pub fn read_certs_and_key(&self) -> io::Result<CertifiedKey> {
     debug!("Read TLS server certificates and private key");
@@ -210,6 +108,12 @@ impl Backend {
   }
 }
 
+/// HashMap and some meta information for multiple Backend structs.
+pub struct Backends {
+  pub apps: HashMap<ServerNameExp, Backend>, // hyper::uriで抜いたhostで引っ掛ける
+  pub default_server_name: Option<ServerNameExp>, // for plaintext http
+}
+
 impl Backends {
   pub async fn generate_server_crypto_with_cert_resolver(&self) -> Result<ServerConfig, anyhow::Error> {
     let mut resolver = ResolvesServerCertUsingSni::new();
diff --git a/src/backend/upstream.rs b/src/backend/upstream.rs
new file mode 100644
index 0000000..da4a97a
--- /dev/null
+++ b/src/backend/upstream.rs
@@ -0,0 +1,109 @@
+use super::{PathNameExp, UpstreamOption};
+use crate::log::*;
+use rand::Rng;
+use rustc_hash::{FxHashMap as HashMap, FxHashSet as HashSet};
+use std::{
+  borrow::Cow,
+  sync::{
+    atomic::{AtomicUsize, Ordering},
+    Arc,
+  },
+};
+
+#[derive(Debug, Clone)]
+pub struct ReverseProxy {
+  pub upstream: HashMap<PathNameExp, UpstreamGroup>, // TODO: HashMapでいいのかは疑問。max_by_keyでlongest prefix matchしてるのも無駄っぽいが。。。
+}
+
+impl ReverseProxy {
+  pub fn get<'a>(&self, path_str: impl Into<Cow<'a, str>>) -> Option<&UpstreamGroup> {
+    // trie使ってlongest prefix match させてもいいけどルート記述は少ないと思われるので、
+    // コスト的にこの程度で十分
+    let path_lc = path_str.into().to_ascii_lowercase();
+    let path_bytes = path_lc.as_bytes();
+
+    let matched_upstream = self
+      .upstream
+      .iter()
+      .filter(|(route_bytes, _)| {
+        match path_bytes.starts_with(route_bytes) {
+          true => {
+            route_bytes.len() == 1 // route = '/', i.e., default
+            || match path_bytes.get(route_bytes.len()) {
+              None => true, // exact case
+              Some(p) => p == &b'/', // sub-path case
+            }
+          }
+          _ => false,
+        }
+      })
+      .max_by_key(|(route_bytes, _)| route_bytes.len());
+    if let Some((_path, u)) = matched_upstream {
+      debug!(
+        "Found upstream: {:?}",
+        String::from_utf8(_path.to_vec()).unwrap_or_else(|_| "<none>".to_string())
+      );
+      Some(u)
+    } else {
+      None
+    }
+  }
+}
+
+#[allow(dead_code)]
+#[derive(Debug, Clone)]
+pub enum LoadBalance {
+  RoundRobin,
+  Random,
+}
+impl Default for LoadBalance {
+  fn default() -> Self {
+    Self::RoundRobin
+  }
+}
+
+#[derive(Debug, Clone)]
+pub struct Upstream {
+  pub uri: hyper::Uri, // base uri without specific path
+}
+
+#[derive(Debug, Clone)]
+pub struct UpstreamGroup {
+  pub upstream: Vec<Upstream>,
+  pub path: PathNameExp,
+  pub replace_path: Option<PathNameExp>,
+  pub lb: LoadBalance,
+  pub cnt: UpstreamCount, // counter for load balancing
+  pub opts: HashSet<UpstreamOption>,
+}
+
+#[derive(Debug, Clone, Default)]
+pub struct UpstreamCount(Arc<AtomicUsize>);
+
+impl UpstreamGroup {
+  pub fn get(&self) -> Option<&Upstream> {
+    match self.lb {
+      LoadBalance::RoundRobin => {
+        let idx = self.increment_cnt();
+        self.upstream.get(idx)
+      }
+      LoadBalance::Random => {
+        let mut rng = rand::thread_rng();
+        let max = self.upstream.len() - 1;
+        self.upstream.get(rng.gen_range(0..max))
+      }
+    }
+  }
+
+  fn current_cnt(&self) -> usize {
+    self.cnt.0.load(Ordering::Relaxed)
+  }
+
+  fn increment_cnt(&self) -> usize {
+    if self.current_cnt() < self.upstream.len() - 1 {
+      self.cnt.0.fetch_add(1, Ordering::Relaxed)
+    } else {
+      self.cnt.0.fetch_and(0, Ordering::Relaxed)
+    }
+  }
+}
diff --git a/src/backend_opt.rs b/src/backend/upstream_opts.rs
similarity index 100%
rename from src/backend_opt.rs
rename to src/backend/upstream_opts.rs
diff --git a/src/config/parse.rs b/src/config/parse.rs
index 4fe244e..19b080f 100644
--- a/src/config/parse.rs
+++ b/src/config/parse.rs
@@ -1,7 +1,6 @@
 use super::toml::{ConfigToml, ReverseProxyOption};
 use crate::{
-  backend::{Backend, PathNameLC, ReverseProxy, UpstreamGroup},
-  backend_opt::UpstreamOption,
+  backend::{Backend, PathNameExp, ReverseProxy, UpstreamGroup, UpstreamOption},
   constants::*,
   error::*,
   globals::*,
@@ -192,7 +191,7 @@ pub fn parse_opts(globals: &mut Globals) -> std::result::Result<(), anyhow::Erro
 }
 
 fn get_reverse_proxy(rp_settings: &[ReverseProxyOption]) -> std::result::Result<ReverseProxy, anyhow::Error> {
-  let mut upstream: HashMap<PathNameLC, UpstreamGroup> = HashMap::default();
+  let mut upstream: HashMap<PathNameExp, UpstreamGroup> = HashMap::default();
   rp_settings.iter().for_each(|rpo| {
     let path = match &rpo.path {
       Some(p) => p.as_bytes().to_ascii_lowercase(),
diff --git a/src/handler/handler_main.rs b/src/handler/handler_main.rs
index b85eb55..045b190 100644
--- a/src/handler/handler_main.rs
+++ b/src/handler/handler_main.rs
@@ -1,7 +1,7 @@
 // Highly motivated by https://github.com/felipenoris/hyper-reverse-proxy
-use super::{utils_headers::*, utils_request::*, utils_response::ResLog, utils_synth_response::*};
+use super::{utils_headers::*, utils_request::*, utils_synth_response::*};
 use crate::{
-  backend::{ServerNameLC, UpstreamGroup},
+  backend::{ServerNameExp, UpstreamGroup},
   error::*,
   globals::Globals,
   log::*,
@@ -39,9 +39,8 @@ where
     client_addr: SocketAddr, // アクセス制御用
     listen_addr: SocketAddr,
     tls_enabled: bool,
-    tls_server_name: Option<ServerNameLC>,
+    tls_server_name: Option<ServerNameExp>,
   ) -> Result<Response<Body>> {
-    req.log_debug(&client_addr, Some("(from Client)"));
     ////////
     let mut log_data = MessageLog::from(&req);
     log_data.client_addr(&client_addr);
@@ -102,7 +101,6 @@ where
       return self.return_with_error_log(StatusCode::SERVICE_UNAVAILABLE, &mut log_data);
     };
     // debug!("Request to be forwarded: {:?}", req_forwarded);
-    req.log_debug(&client_addr, Some("(to Backend)"));
     log_data.xff(&req.headers().get("x-forwarded-for"));
     log_data.upstream(req.uri());
     //////
@@ -123,14 +121,9 @@ where
       }
     };
 
-    res_backend.log_debug(&backend.server_name, &client_addr, Some("(from Backend)"));
-    // let response_log = res_backend.status().to_string();
-
     if res_backend.status() != StatusCode::SWITCHING_PROTOCOLS {
       // Generate response to client
       if self.generate_response_forwarded(&mut res_backend).is_ok() {
-        // info!("{} => {}", request_log, response_log);
-        res_backend.log_debug(&backend.server_name, &client_addr, Some("(to Client)"));
         log_data.status_code(&res_backend.status()).output();
         return Ok(res_backend);
       } else {
diff --git a/src/handler/mod.rs b/src/handler/mod.rs
index 4f26d27..799ef60 100644
--- a/src/handler/mod.rs
+++ b/src/handler/mod.rs
@@ -1,7 +1,6 @@
 mod handler_main;
 mod utils_headers;
 mod utils_request;
-mod utils_response;
 mod utils_synth_response;
 
 pub use handler_main::HttpMessageHandler;
diff --git a/src/handler/utils_headers.rs b/src/handler/utils_headers.rs
index dc956aa..acb929e 100644
--- a/src/handler/utils_headers.rs
+++ b/src/handler/utils_headers.rs
@@ -1,4 +1,9 @@
-use crate::{backend::UpstreamGroup, backend_opt::UpstreamOption, error::*, log::*, utils::*};
+use crate::{
+  backend::{UpstreamGroup, UpstreamOption},
+  error::*,
+  log::*,
+  utils::*,
+};
 use bytes::BufMut;
 use hyper::{
   header::{self, HeaderMap, HeaderName, HeaderValue},
diff --git a/src/handler/utils_request.rs b/src/handler/utils_request.rs
index 9ff480d..b36bc5e 100644
--- a/src/handler/utils_request.rs
+++ b/src/handler/utils_request.rs
@@ -1,58 +1,5 @@
-use crate::{error::*, log::*, utils::*};
+use crate::error::*;
 use hyper::{header, Request};
-use std::fmt::Display;
-
-////////////////////////////////////////////////////
-// Functions of utils for request messages
-pub trait ReqLog {
-  fn log<T: Display + ToCanonical>(self, src: &T, extra: Option<&str>);
-  fn log_debug<T: Display + ToCanonical>(self, src: &T, extra: Option<&str>);
-  fn build_message<T: Display + ToCanonical>(self, src: &T, extra: Option<&str>) -> String;
-}
-impl<B> ReqLog for &Request<B> {
-  fn log<T: Display + ToCanonical>(self, src: &T, extra: Option<&str>) {
-    info!("{}", &self.build_message(src, extra));
-  }
-  fn log_debug<T: Display + ToCanonical>(self, src: &T, extra: Option<&str>) {
-    debug!("{}", &self.build_message(src, extra));
-  }
-  fn build_message<T: Display + ToCanonical>(self, src: &T, extra: Option<&str>) -> String {
-    let canonical_src = src.to_canonical();
-
-    let host = self
-      .headers()
-      .get(header::HOST)
-      .map_or_else(|| "", |v| v.to_str().unwrap_or(""));
-    let uri_scheme = self
-      .uri()
-      .scheme_str()
-      .map_or_else(|| "".to_string(), |v| format!("{}://", v));
-    let uri_host = self.uri().host().unwrap_or("");
-    let uri_pq = self.uri().path_and_query().map_or_else(|| "", |v| v.as_str());
-    let ua = self
-      .headers()
-      .get(header::USER_AGENT)
-      .map_or_else(|| "", |v| v.to_str().unwrap_or(""));
-    let xff = self
-      .headers()
-      .get("x-forwarded-for")
-      .map_or_else(|| "", |v| v.to_str().unwrap_or(""));
-
-    format!(
-      "{} <- {} -- {} {} {:?} -- ({}{}) \"{}\" \"{}\" {}",
-      host,
-      canonical_src,
-      self.method(),
-      uri_pq,
-      self.version(),
-      uri_scheme,
-      uri_host,
-      ua,
-      xff,
-      extra.unwrap_or("")
-    )
-  }
-}
 
 pub trait ParseHost {
   fn parse_host(&self) -> Result<&[u8]>;
diff --git a/src/handler/utils_response.rs b/src/handler/utils_response.rs
deleted file mode 100644
index c04b7f6..0000000
--- a/src/handler/utils_response.rs
+++ /dev/null
@@ -1,41 +0,0 @@
-use crate::{log::*, utils::*};
-use hyper::Response;
-use std::fmt::Display;
-
-////////////////////////////////////////////////////
-// Functions of utils for request messages
-pub trait ResLog {
-  fn log<T1: Display, T2: Display + ToCanonical>(self, server_name: &T1, client_addr: &T2, extra: Option<&str>);
-  fn log_debug<T1: Display, T2: Display + ToCanonical>(self, server_name: &T1, client_addr: &T2, extra: Option<&str>);
-  fn build_message<T1: Display, T2: Display + ToCanonical>(
-    self,
-    server_name: &T1,
-    client_addr: &T2,
-    extra: Option<&str>,
-  ) -> String;
-}
-impl<B> ResLog for &Response<B> {
-  fn log<T1: Display, T2: Display + ToCanonical>(self, server_name: &T1, client_addr: &T2, extra: Option<&str>) {
-    info!("{}", &self.build_message(server_name, client_addr, extra));
-  }
-  fn log_debug<T1: Display, T2: Display + ToCanonical>(self, server_name: &T1, client_addr: &T2, extra: Option<&str>) {
-    debug!("{}", &self.build_message(server_name, client_addr, extra));
-  }
-  fn build_message<T1: Display, T2: Display + ToCanonical>(
-    self,
-    server_name: &T1,
-    client_addr: &T2,
-    extra: Option<&str>,
-  ) -> String {
-    let canonical_client_addr = client_addr.to_canonical();
-    format!(
-      "{} <- {} -- {} {:?} {}",
-      canonical_client_addr,
-      server_name,
-      self.status(),
-      self.version(),
-      // self.headers(),
-      extra.map_or_else(|| "", |v| v)
-    )
-  }
-}
diff --git a/src/main.rs b/src/main.rs
index 1e2996c..b69acd6 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -6,7 +6,6 @@ use tikv_jemallocator::Jemalloc;
 static GLOBAL: Jemalloc = Jemalloc;
 
 mod backend;
-mod backend_opt;
 mod config;
 mod constants;
 mod error;
@@ -17,7 +16,7 @@ mod proxy;
 mod utils;
 
 use crate::{
-  backend::{Backend, Backends, ServerNameLC},
+  backend::{Backend, Backends, ServerNameExp},
   config::parse_opts,
   constants::*,
   error::*,
@@ -73,7 +72,7 @@ fn main() {
       runtime_handle: runtime.handle().clone(),
       backends: Backends {
         default_server_name: None,
-        apps: HashMap::<ServerNameLC, Backend>::default(),
+        apps: HashMap::<ServerNameExp, Backend>::default(),
       },
 
       sni_consistency: true,
diff --git a/src/proxy/proxy_h3.rs b/src/proxy/proxy_h3.rs
index 5892b1d..0599a61 100644
--- a/src/proxy/proxy_h3.rs
+++ b/src/proxy/proxy_h3.rs
@@ -1,5 +1,5 @@
 use super::Proxy;
-use crate::{backend::ServerNameLC, error::*, log::*};
+use crate::{backend::ServerNameExp, error::*, log::*};
 use bytes::{Buf, Bytes};
 use h3::{quic::BidiStream, server::RequestStream};
 use hyper::{client::connect::Connect, Body, Request, Response};
@@ -10,7 +10,7 @@ impl<T> Proxy<T>
 where
   T: Connect + Clone + Sync + Send + 'static,
 {
-  pub(super) async fn connection_serve_h3(self, conn: quinn::Connecting, tls_server_name: ServerNameLC) -> Result<()> {
+  pub(super) async fn connection_serve_h3(self, conn: quinn::Connecting, tls_server_name: ServerNameExp) -> Result<()> {
     let client_addr = conn.remote_address();
 
     match conn.await {
@@ -68,7 +68,7 @@ where
     req: Request<()>,
     stream: RequestStream<S, Bytes>,
     client_addr: SocketAddr,
-    tls_server_name: ServerNameLC,
+    tls_server_name: ServerNameExp,
   ) -> Result<()>
   where
     S: BidiStream<Bytes> + Send + 'static,
diff --git a/src/proxy/proxy_main.rs b/src/proxy/proxy_main.rs
index 0af1f3e..f3cf3b7 100644
--- a/src/proxy/proxy_main.rs
+++ b/src/proxy/proxy_main.rs
@@ -1,5 +1,5 @@
 // use super::proxy_handler::handle_request;
-use crate::{backend::ServerNameLC, error::*, globals::Globals, handler::HttpMessageHandler, log::*};
+use crate::{backend::ServerNameExp, error::*, globals::Globals, handler::HttpMessageHandler, log::*};
 use hyper::{client::connect::Connect, server::conn::Http, service::service_fn, Body, Request};
 use std::{net::SocketAddr, sync::Arc};
 use tokio::{
@@ -50,7 +50,7 @@ where
     stream: I,
     server: Http<LocalExecutor>,
     peer_addr: SocketAddr,
-    tls_server_name: Option<ServerNameLC>,
+    tls_server_name: Option<ServerNameExp>,
   ) where
     I: AsyncRead + AsyncWrite + Send + Unpin + 'static,
   {