If you're looking for manga similar to Kodomo no Jikan: Rin's Classroom Diary, you might like these titles.
Takayama, a teacher living his teacher's life "going on with the flow", is being scolded for his lazy attitude by Fuyuno, the most talented female student in his grade. In fact, Fuyuno has special feelings for Takayama...? Can the forbidden love between a teacher and a female student be avoided?
Wataru, a lazy high school student, is visited by the earnest and slightly airheaded teacher, Runa-sensei. So that Wataru can become a respectable adult, she gently starts giving him naughty private lessons.
Senior high schooler Hikaru Umino is desperately in love with his teacher, Kuniaki Shima. When he hears a rumor that Shima is engaged to be married, Hikaru does the unthinkable and forces himself on his teacher. Shima makes him atone for his sin by, unexpectedly, becoming “make-believe” lovers until Hikaru graduates high school. When the time limit expires, can Hikaru let go of his beloved teacher?
Enter Kadokura Kyouko, grade school teacher, 33 years old, single. She has a gentle and caring personality and loves her job. Unfortunately she is only popular with her pupils, so her prospects of ever getting married seem? grim. Also enter Yamato Kazuki, university student, 20 years old, with future goals of marrying Kyouko-sensei and becoming an astronaut. He's been in love with Kyouko-sensei ever since she became his homeroom teacher in 4th grade. Now finally an adult and having enough money to buy a ring, he decides to propose to her and she - in some way or another - agrees to become his girlfriend. But even though theoretically a couple now, their teacher-student relationship doesn't seem to have changed much. What will become of this unlikely pair?
A 41-year-old teacher and a 14-year-old middle schooler. What would happen if his student, young enough to be his daughter, were possessed by his deceased wife...?
A cram school teacher, Uno, reunites with his former student and lover, Someya. Uno, who couldn't throw away his feelings for Someya, accepts his proposal to "be in a no-strings attached lover's relationship" and sleeps with him. The two spend their days peacefully and happily like the time when they were lovers. Then, by chance, he happens to witness Someya entering a love hotel with a woman. Uno presses for the truth, but senses something wrong with Someya's reaction...
I'm 24, a teacher, and... I'm being hit on by my 17-year-old student in front of his classmates. What kind of joke is this!? He steals a kiss from me after class ends one day, and even though I promptly stop it, just that one little kiss sends me reeling! He's my student, and yet all I want to do is stare at him... Into those beautiful eyes... Which will win; a student's lust or a teacher's logic?
Emiri, a 23-year-old high school teacher, makes love once with 18-year-old Shishioh (meaning Lion King) and they decide to get married. Shishioh transfers to the school where Emiri teaches.