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.

Later on in the series, Ren develops a drug addiction and his life starts to spiral out of control. Shortly after begging his manager for more drugs, on his knees, quivering in pain from withdrawal, he dies.

He dies from a car crash. Reporters were following him and happened to see it. While driving, Ren sees a black cat, and thinking it is Nana (due to the hallucinogenics ), swerves into a building, which happened to be where he's lived all of his life in. No one is really sure if it was a suicide attempt or accidental. Crashing into that building does make it seem like a suicide attempt, but his body was found with both of his hands covering his chest and unscathed, which the doctors in the manga say it indicates Ren tried to protect his hands when he realized the car went out of control, thus an accident. Takumi also believes that the incident was not suicidal after seeing his body, because Ren protected his precious music playing hands. Ren's face was unidentifiable due to how severe the accident was.