Shun Midorikawa is a member of Kusakabe Unit. Yoneya likened Midorikawa's personality to a "puppy dying to show off its talents". This was shown when he humiliated Osamu by defeating him effortlessly ten times in front of a large crowd. However, in front of Jin, he acted very silly and energetic, because Jin saved Midorikawa in the past.
(Source: World Trigger Wikia)