diff --git a/.gitignore b/.gitignore
index 3f100fd..3531062 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,5 @@
 *.swp
-*.csv
+cache
 log
+*.csv
+*.html
diff --git a/clean b/clean
index fbe59c5..f8f40c5 100755
--- a/clean
+++ b/clean
@@ -1,3 +1,5 @@
 #!/bin/sh
+rm -rf cache
 rm -rf log
 rm -f *.csv
+rm -f *.html
diff --git a/update b/update
index f607abd..1647d08 100755
--- a/update
+++ b/update
@@ -5,7 +5,7 @@ CSV_URL="https://www8.cao.go.jp/chosei/shukujitsu/syukujitsu.csv"
 MAIL_TO="$USER"
 MAIL_FROM="info@holiday.kareha.org"
 MAIL_SUBJECT="Holiday CSV Updated"
-MAIL_BODY="Holiday CSV file has been Updated."
+MAIL_BODY="Holiday CSV file has been updated."
 
 # Constants
 EXIT_SUCCESS=0
@@ -25,10 +25,10 @@ verify_command "awk"
 verify_command "mailx"
 
 # Logging
-CURRENT_MONTH=$(date "+%Yw%U%z")
+CURRENT_MONTH=$(date "+%Y-%m%z")
 SCRIPT_NAME=$(basename $0)
 LOG_DIR="log"
-LOG_FILE="$LOG_DIR/$SCRIPT_NAME_$CURRENT_MONTH"
+LOG_FILE="$LOG_DIR/$SCRIPT_NAME-$CURRENT_MONTH"
 
 get_current_time() {
   date "+%Y-%m-%d %H:%M:%S%z"
@@ -48,7 +48,7 @@ send_mail() {
 }
 
 # Acquire the lock or exit
-LOCK_DIR="lock"
+LOCK_DIR="$SCRIPT_NAME-lock"
 if ! mkdir "$LOCK_DIR" 2>/dev/null; then
   echo "Another process is holding the lock. Exiting."
   exit $EXIT_FAILURE
@@ -65,6 +65,10 @@ CSV_FILE="holidays-jp.csv"
 # Run
 curl -sS -L -o $TMP_CSV_FILE $CSV_URL
 if ! diff -q $RAW_CSV_FILE $TMP_CSV_FILE >/dev/null 2>&1; then
+  CACHE_DIR="cache"
+  mkdir -p "$CACHE_DIR"
+  CURRENT_DATETIME=$(date "+%Y-%m-%d_%H:%M:%S%z")
+  cp $TMP_CSV_FILE "$CACHE_DIR/holidays-jp-$CURRENT_DATETIME.csv"
   mv $TMP_CSV_FILE $RAW_CSV_FILE
   nkf -w $RAW_CSV_FILE >$ALL_CSV_FILE
   current_year=$(date +'%Y')
diff --git a/watch b/watch
new file mode 100755
index 0000000..22376c7
--- /dev/null
+++ b/watch
@@ -0,0 +1,80 @@
+#!/bin/sh
+
+# Settings
+SITE_URL="https://www8.cao.go.jp/chosei/shukujitsu/gaiyou.html"
+MAIL_TO="$USER"
+MAIL_FROM="info@holiday.kareha.org"
+MAIL_SUBJECT="Holiday Site Updated"
+MAIL_BODY="Holiday web site has been updated."
+
+# Constants
+EXIT_SUCCESS=0
+EXIT_FAILURE=1
+
+# Verify the required runtime environment
+verify_command() {
+  if ! command -v $1 >/dev/null; then
+    echo "This script requires \"$1\" to be installed. Please install it and try again."
+    exit $EXIT_FAILURE
+  fi
+}
+
+verify_command "curl"
+verify_command "mailx"
+
+# Logging
+CURRENT_MONTH=$(date "+%Y-%m%z")
+SCRIPT_NAME=$(basename $0)
+LOG_DIR="log"
+LOG_FILE="$LOG_DIR/$SCRIPT_NAME-$CURRENT_MONTH"
+
+get_current_time() {
+  date "+%Y-%m-%d %H:%M:%S%z"
+}
+
+log() {
+  local timestamp=$(get_current_time)
+  local message=$1
+  echo "$timestamp $message" >>$LOG_FILE
+}
+
+send_mail() {
+  echo "$MAIL_BODY" | mailx -r "$MAIL_FROM" -s "$MAIL_SUBJECT" "$MAIL_TO"
+  if [ $? -ne 0 ]; then
+    log "Failed to send email"
+  fi
+}
+
+# Acquire the lock or exit
+LOCK_DIR="$SCRIPT_NAME-lock"
+if ! mkdir "$LOCK_DIR" 2>/dev/null; then
+  echo "Another process is holding the lock. Exiting."
+  exit $EXIT_FAILURE
+fi
+
+mkdir -p $LOG_DIR
+
+# Internal configuration settings
+TMP_HTML_FILE="summary-jp-tmp.html"
+HTML_FILE="summary-jp.html"
+
+# Run
+curl -sS -L -o $TMP_HTML_FILE $SITE_URL
+if ! diff -q $HTML_FILE $TMP_HTML_FILE >/dev/null 2>&1; then
+  CACHE_DIR="cache"
+  mkdir -p "$CACHE_DIR"
+  CURRENT_DATETIME=`date "+%Y-%m-%d_%H:%M:%S%z"`
+  cp $TMP_HTML_FILE "$CACHE_DIR/summary-jp-$CURRENT_DATETIME.html"
+  mv $TMP_HTML_FILE $HTML_FILE
+  log "Changed"
+  send_mail
+else
+  log "No Change"
+  rm $TMP_HTML_FILE
+fi
+
+# Release the lock
+rmdir "$LOCK_DIR"
+
+# Exit
+exit $EXIT_SUCCESS