Based on the idea of KaraNagai's Kana Tutorial site that uses PHP backend, I decided to create an offline version of similar Javascript application that I can take with me when I am not online. I hope this is taken as a compliment to KaraNagai's work. Please give it a try.
Requirement: Your OS need to be able to display Japanese character. If you don't see the Japanese character, you need to install the Japanese language pack for your OS.