While taking their usual bath, the boys discuss how much Kyotaro is like an old man. The next day, when they go to school, they find themselves exhausted by climbing up the stairs... and learn that they're all becoming old men!
The Suddenness of HAPPY! KISS
HAPPY Recipe
HAPPY Ice Cream
It's A Wonderful HAPPY
HAPPY and Beautiful
HAPPY Identity
Let's happy kiss our way to HAPPY Flutter Kicks
HAPPY Endless Summer
HAPPY Dice
HAPPY Old Men
One Centimeter to HAPPY
Always HAPPY in the Heart!