Kouhai

[Sarah]

Someone who wants to be noticed by Senpai.

[Rihanna]

A kouhai is your junior at work, school, or a group. Usually they belong to the same organization as you but they entered the organization after you. A kouhai could also be someone who has entered the same industry as you but at a later date. In this case industry has a very broad meaning, e.g. the entertainment industry, a professional sports league.