Shinen naru Ren'ai Tetsugaku: Do-S Kyouju ga Watashi o Dekiai Suru Riyuu

Tomomi, a graduate student in the philosophy department, had a crush on Professor Takatsuki, who was famous for being a strict disciplinarian as a teacher. After a drinking party, Takatsuki saved her from being taken away by a male student, but the drunk Tomomi thought that the professor treating her so kindly was all just a dream. When she woke up the next morning, she found herself in Takatsuki's bed. As Tomomi worried about her future in the department, Takatsuki made a proposal to her: "Why don't you marry me?" (Source: eBookJapan, translated)