Chinen was the Head of Housen Academy during the time of the Umehoshi Brothers. The Twins had known Ryuutarou throughout middle school. During his 2nd year, he was jumped by a fellow Housen student Nikaidou Takuya.
Before the jumping, Housen was already in a power struggle between Chinen and Nikaidou.
It was said that Chinen was an idiot but he at the same time sensible.