Kōyū

Kōyū (交友, Kouyuu) is Riyan's personal wolf-summon, as well as the leader of all wolf and dog summons. The two are extremely good partners, having made a number of Collaboration ninjutsu together, and can sync chakra with one another from over a mile away.

Personality
Kōyū, like his toad counterpart Gamabunta, is considered old and wise, and is greatly respected by all who know him well enough. In reality, he constantly bickers with Riyan's other dog and wolf summons over small things when they should focus on the bigger picture, such as the fact that a battle will cause them to miss a meal or a nap.

Kōyū is a lazy and unenthusiastic character who apparently spends much of his time asleep and which no one, except Riyan upon summoning him, appears to try and stop him from doing. Despite being the highest-ranking dog or wolf summoning creature, he is not eager to take a leadership role. He is not particularly interested in whatever is going on around him, although he is surprisingly observant and a capable analyst.

He can be serious on occasion, although his personality does not change much; he comes off as reluctant, but nonetheless willing to complete the task at hand.

Trivia

 * Kōyū is the japanese word for "companion", obviously referring to the relationship between canines and humans.