Curious, seductive and popular, Hiro is always ready to go on an adventure. He is a faithful friend to Ren and Koichi, and would never hesitate to put himself in danger to help them out. However his appetite for risk and adventure can sometimes lead him into complicated situations.

He falls under the spell of the mysterious girl in the club and by accepting a diamond-shaped object that appears to be more attractive than dangerous he leads his friends straight into the trap of tobacco.