Johnny

Johnny in the gym.

Johnny is Hiroki's best friend and was introduced as a new character in Straight to Heart. He is in the same grade as Hiroki and has a big crush on Yumi. He and Hiroki are great locksmiths, as seen on Hot Shower. He is always trying to think of ways to win over Yumi. In the episode The Pretender he got an advice from Ulrich to follow Yumi around all the time. Yumi didn't like this at all, and became angry with Ulrich for doing such a thing. But after a Time Reversion, Ulrich got a chance to make up for his mistake, and Yumi and Johnny got along very well in the end.
He has made appearances in other episodes since that time. These episodes include Skidbladnir, Hot Shower, and Canine Conundrum. In the latter, he attended Jim's Pencak Silat class (mainly only to be with Yumi).