Blast's former bassist, Ren is actually Trapnest's guitarist. He is very popular and his music is well-received by fans. He and Nana Osaki were once in a relationship. Ren is a big fan of the Sex Pistols; he participated in a tribute album to them, and wears a "Sid Vicious" padlock around his neck that he received from Nana. Nana had an image of a lotus tattooed on her upper arm in honor of him ("Ren" is a Japanese name for lotus). The brand of the cigarettes he originally smoked was the 'Seven Stars'.

Nana first met him through Nobu, who really just admired him from afar. Ren was popular around their hometown for supposedly being found as a baby in an abandoned warehouse, which he lives in to this day. He isn't ashamed of this; he actually brags about it.

Ren and Nana are proven to be very similar throughout the series, but they are not totally similar. Ren seems to be more open with his love for Nana, being able to ask for her back and her hand in marriage while those thoughts just made Nana want to yell at him. Ren also really would like a family and child, while Nana really dislikes the concept because she doesn't want to be the dependent wife who makes miso soup for her husband all day.