diff --git a/src/library/entry.cr b/src/library/entry.cr
index 9fb1ef9..b43dd77 100644
--- a/src/library/entry.cr
+++ b/src/library/entry.cr
@@ -337,3 +337,145 @@ class ZippedEntry < Entry
     File.exists? @zip_path
   end
 end
+
+class DirectoryEntry < Entry
+  include YAML::Serializable
+
+  getter dir_path : String
+
+  @[YAML::Field(ignore: true)]
+  @sorted_files : Array(String)?
+
+  @signature : String
+
+  def initialize(@dir_path, @book)
+    storage = Storage.default
+    @encoded_path = URI.encode @dir_path
+    @title = File.basename @dir_path
+    @encoded_title = URI.encode @title
+
+    unless File.readable? @dir_path
+      @err_msg = "Directory #{@dir_path} is not readable."
+      Logger.warn "#{@err_msg} Please make sure the " \
+                  "file permission is configured correctly."
+      return
+    end
+
+    unless DirectoryEntry.validate_directory_entry @dir_path
+      @err_msg = "Directory #{@dir_path} is not valid directory entry."
+      Logger.warn "#{@err_msg} Please make sure the " \
+                  "directory has valid images."
+      return
+    end
+
+    size_sum = 0
+    sorted_files.each do |file_path|
+      size_sum += File.size file_path
+    end
+    @size = size_sum.humanize_bytes
+
+    @signature = Dir.directory_entry_signature @dir_path
+    id = storage.get_entry_id @dir_path, @signature
+    if id.nil?
+      id = random_str
+      storage.insert_entry_id({
+        path:      @dir_path,
+        id:        id,
+        signature: @signature,
+      })
+    end
+    @id = id
+
+    mtimes = sorted_files.map { |file_path| File.info(file_path).modification_time }
+    @mtime = mtimes.max
+
+    @pages = sorted_files.size
+  end
+
+  def path : String
+    @dir_path
+  end
+
+  def createtime : Time
+    ctime @dir_path
+  end
+
+  def read_page(page_num)
+    img = nil
+    begin
+      files = sorted_files
+      file_path = files[page_num - 1]
+      data = File.read(file_path).to_slice
+      if data
+        img = Image.new data, MIME.from_filename(file_path),
+          File.basename(file_path), data.size
+      end
+    rescue e
+      Logger.warn "Unable to read page #{page_num} of #{@dir_path}. Error: #{e}"
+    end
+    img
+  end
+
+  def page_dimensions
+    sizes = [] of Hash(String, Int32)
+    sorted_files.each_with_index do |path, i|
+      data = File.read(path).to_slice
+      begin
+        data.not_nil!
+        size = ImageSize.get data
+        sizes << {
+          "width"  => size.width,
+          "height" => size.height,
+        }
+      rescue e
+        Logger.warn "Failed to read page #{i} of entry #{@dir_path}. #{e}"
+        sizes << {"width" => 1000_i32, "height" => 1000_i32}
+      end
+    end
+    sizes
+  end
+
+  def exists? : Bool
+    existence = File.exists? @dir_path
+    return false unless existence
+    files = DirectoryEntry.get_valid_files @dir_path
+    signature = Dir.directory_entry_signature @dir_path
+    existence = files.size > 0 && @signature == signature
+    @sorted_files = nil unless existence
+
+    # For more efficient,
+    # Fix a directory instance with new property
+    # and return true
+    existence
+  end
+
+  def sorted_files
+    cached_sorted_files = @sorted_files
+    return cached_sorted_files if cached_sorted_files
+    @sorted_files = DirectoryEntry.get_valid_files_sorted @dir_path
+    @sorted_files.not_nil!
+  end
+
+  def self.validate_directory_entry(dir_path)
+    files = DirectoryEntry.get_valid_files dir_path
+    files.size > 0
+  end
+
+  def self.get_valid_files(dir_path)
+    files = [] of String
+    Dir.entries(dir_path).each do |fn|
+      next if fn.starts_with? "."
+      path = File.join dir_path, fn
+      next unless is_supported_image_file path
+      next if File.directory? path
+      next unless File.readable? path
+      files << path
+    end
+    files
+  end
+
+  def self.get_valid_files_sorted(dir_path)
+    files = DirectoryEntry.get_valid_files dir_path
+    files.sort! { |a, b| compare_numerically a, b }
+  end
+end
diff --git a/src/util/signature.cr b/src/util/signature.cr
index 5ca3e14..63d31ce 100644
--- a/src/util/signature.cr
+++ b/src/util/signature.cr
@@ -19,7 +19,7 @@ class File
   #   information as long as the above changes do not happen together with
   #   a file/folder rename, with no library scan in between.
   def self.signature(filename) : UInt64
-    if is_supported_file filename
+    if is_supported_file(filename) || is_supported_image_file(filename)
       File.info(filename).inode
     else
       0u64
@@ -64,6 +64,9 @@ class Dir
         path = File.join dirname, fn
         if File.directory? path
           signatures << Dir.contents_signature path, cache
+          if DirectoryEntry.validate_directory_entry path
+            signatures << Dir.directory_entry_signature path, cache
+          end
         else
           # Only add its signature value to `signatures` when it is a
           #   supported file
@@ -76,4 +79,19 @@ class Dir
     cache[dirname] = hash
     hash
   end
+
+  def self.directory_entry_signature(dirname, cache = {} of String => String)
+    return cache[dirname + "?entry"] if cache[dirname + "?entry"]?
+    Fiber.yield
+    signatures = [] of String
+    image_files = DirectoryEntry.get_valid_files_sorted dirname
+    if image_files.size > 0
+      image_files.each do |path|
+        signatures << File.signature(path).to_s
+      end
+    end
+    hash = Digest::SHA1.hexdigest(signatures.join)
+    cache[dirname + "?entry"] = hash
+    hash
+  end
 end