In an interview with the game's director Naoki Suda published in the 2003 Nintendo Monthly Online, he was asked why he added the character 'Chibi Fumiko' in the game? He responded:

"As we approached the end of the development, we realized we'd forgotten to include a hidden character. One day I remembered "Chibi Fumiko" from the comic anthology for the first game. She was created specifically for that comic, at the request of the writer, and we never had any intention of using her in-game… but given the situation we found ourselves in, I thought, "We can use this!!!" and we hurriedly added her."
Contributed by ProtoSnake