Goukaku no Tame no! Yasashii Sankaku Kankei Nyuumon

In pursuit of Akira, the senpai she admires and loves, Mayuki Yukishita does her best to pass her exams and get into the same school as her, only to end up dead last on a mock test. To help her out, her mom gets her a private tutor, Rin Mochizuki, a polyamorous girl from the same school as her senpai who ends up taking Mayuki's first kiss, and who is closer to Akira than Mayuki knows...