Monotone Blue  (English, Paperback, Nagabe)

Hachi the cat finds most things monotonous, but at the top of his list is high school and all that comes with it. But when Aoi the lizard - a quiet, high-achieving transfer student - arrives, Hachi catches a glimpse of a brighter, more colourful life. If Hachi can help Aoi open up, unlocking new feelings in the process, maybe his life won't be so bland, after all.