Holstein Trio

The Holstein Trio are a group of three third-year students in the Holstein Club that are obsessed with breeding beautiful Holstein cows.

Personality
The trio is often seen to be acting in a perverted sort of way, and it always leads its way back to Holstein cows and breeding them or grooming them to be beautiful. They are deceptively very bright individuals, able to use complicated lab equipment with a high understanding of science related to dairy and cows.

Like many of the characters in the story, they have very focused knowledge, and their subject of knowledge is cows.

Shinnosuke Aikawa
Aikawa joins the Holstein club partially because he likes to see the livestock outside of class but also to learn from the seniors about using the lab equipment the school grants access to. He understands that the Holstein Trio is not a very serious group, but is likely friends with them as later on his room is shown to be decorated wall to wall with cow themed items, much like the Holstein Club room.