因吹思婷;-)

什么鬼

什么鬼！！！哈哈哈。

Each encode with the key is independent of any other encode with the key. Each decode with the key is independent of any other decode with the key.

Would these two sentences help?

Edit: also, the kana tests with non-Latin characters were meant to help my fellow Westerners be aware that this encryption algorithm can be used for any ordered set of characters. If you would like to contribute to this kata, that could be something you could add (or I could add and assign credit to you).

If you've completed the other Vigenere cipher kata, you should be relatively good for this one. The major difference is that the decoded/encoded text influences the decryption/encryption, respectively. Try to read the description more carefully.