Jinnai was a loyal follower of Akame of the Iga Clan.
Jinnai is white Kishu Inu.
He is loyal to Akame, he is skilled and brave ninja dog and considers Kirikaze a great ally.
Ginga Nagareboshi Gin
Jinnai goes with Kirikaze, Akame, and Gin to get healing herbs from the Kouga territory. When Akame stays alone to fight the enemy in order for the others to escape, he tells Kirikaze not to turn back.
After the death of Kurojaki and the Kouga dogs, the remaining Iga dogs, including Akame, Kirikaze, and Jinnai joined Gin's pack. Unfortunately, Jinnai didn't live to experience the final battle against Akakabuto as he was killed by the bear Madara as he accidentally fell into his mouth while using a shinobi technique. He seemed to be close with Kirikaze.
"Shinobi doesn't work through feelings but orders!"
-Jinnai to Kirikaze. Ginga Nagareboshi Gin, volume 6
See more pictures in Jinnai/Gallery.