Kasuga Riku

Shakuhi took him in after he had been a vegetative for a long time, and remodeled his body.

Shakuhi is his parent. He follows Shakuhi around to be her assistant.

He is a boy with a friendly personality.

Shuffle ~Bokura wa Omoi o Tokihanatsu~ Proflie

Shakuhi took him in after he had been in a coma for a long time, and had him remodeled.
He used to be sincere and mild-mannered, but after losing Shakuhi, who used to be his parent, he became a cold-hearted person.
He has become cold-hearted after losing Shakuhi, who was his parental figure.