OC designed for  ElCid, another one done earlier this month.

Sayu is the smartest in her year as well as the president of her school's science club, and this stoic genius is always cooking up some new ideas. She loves nothing more than creating devices and chemical concoctions that she talks her friends into testing out for her, especially Haneko. From growth serums to machines that seem to serve no non-specialty purposes, the sika deer has made many scientific discoveries, whether on accident or on purpose, and many of them coincidentally manage to help her figure out what she's into, and to help her friends discover some of their own!