Nonohara Yuzuka no Himitsu no Haishin 1

Yuka, a girl who suffers from social isolation at school, has a secret: she is an online erotic streaming star, concealing her identity with a mask. One day, she finds what appears to be a love letter in her locker, but it actually contains screenshots from her streams. The man behind the letter blackmails her, threatening to expose her identity unless she complies with his demands.