Hibike! Euphonium Specials Episode 4

All Hail Tuba Kun! (チューバ君は王子様なのバス!) is the fourth OVA episode of the first season of the Hibike! Euphonium anime series. It was broadcasted on September 16, 2015.

Synopsis
Kumiko notices the Tuba-kun band-aids on Midori fingers. Midori states that she is enamored by Tuba-kun and has pretty much every merchandise of him, except the capsule toy.

When Midori was in middle school, she took her little sister, Kohaku to the park, who naturally wandered off to a handshake greeting while Midori was gone. That's when a Tuba-kun mascot brought back Kohaku to Midori.