Sakuichi Teijin

Sakuichi is the second son of the Teijin family, set to inherit Teijin Corporation due to his older brother's lack of interest in it. He has been friends with Ryota (the only one who is allowed to call him "Saku") since they were kids, and harbored romantic feelings for him for years until they were finally reunited in Japan after Saku finished his studies in America.

Saku tends to get jealous and pouts whenever Ryota is paying attention to other men, particularly Takahiro (who uses the opportunity to tease Saku even more). While in public he projects an aura of maturity and dependability, he lets his childish side show when he's around Ryota.