Re-encounter

6 ch
uni student x uni student
first met as middle school students
omegaverse

Kaede (alpha) saves Azusa, an omega that was being bullied, and moves to another city right after. Many years later, they meet again and Azusa says that he wants to pay him back and that he'll do anything if Kaede gives him a chance. Fortunately or unfortunately, playboy Kaede just can't reject such an opportunity of amusement.

Ongoing manga
2 couples, interconnected
2nd couple: Hwa and Seolhyun
uni student x uni student
first met as kids

17 ch
uni student x uni student
first met as hs students

In college, Naoto has an unexpected reunion with ex-boyfriend Taichi who he broke up with for denouncing him as "sexual gratification". Naoto had been firmly influenced by his hatred of this past incident but, little by little his heart is starting to forgive Taichi who has really grown when compared to their time in high school.

9 ch
hs student x hs student
first met as kids

While buying food at the supermarket, Sunao Morihara gets kidnapped by a strange man, Kuon Tachibana, who turns out to be incredibly rich! His motive? He wants Sunao to be his friend. However, before Sunao realizes, being Kuon's "friend" actually means becoming his wife!

5 ch
hs student x hs student
first met as kids

Chiharu Saeki and Wataru Toda are two high school students who share a common hobby–they love to watch movies. After they meet, they become fast friends until one day, their relationship takes a sudden twist. What does it mean to love someone? What can you really do about it?

Sequel: http://www.mangago.me/read-manga/kimi_to_natsu_no_naka/

7 ch
uni student x uni student
first met as hs students

Junpei Shishido is a friendly guy who gets along well with anyone and everyone. One day, he meets a young man at university who acts aloof and distant towards him, and yet he looks familiar…?

4 ch
hs student x hs student
first met as kids

Suzuki Kojirou (his Kago is Efreet) is a member of the public morals committee at a high school which gathers a lot of students whose “Kago” powers are stronger than normal people.

5 ch
office worker x office worker
first met as hs students

Yuzuru ran away from Daisuke after high school but bumped into him again years later at his company. Was it fate or is everything going according to Daisuke's plan. Can Yuzuru really win against the married Daisuke?

Ongoing manga
office worker x uni student
first met 4 years before start of story

Ayase Yukiya is a university student whose cousin Tetsuo Ishii betrays him and sells him in an auction to settle his heavy debts. Ayase is bought by Somuku Kanou for 1.2 billion yen. The reason behind Kanou doing this is Kanou remembers Ayase from four years ago, when Ayase, a stranger, helped him. Now Kanou wants to keep Ayase close to him in order to protect him.

6 ch
uni student x actor
first met as hs students

College student Haneji Kaoru is surprised when popular actor Aragaki Jin appears in his workplace. They were high school friends, but unable to cope with his deepening feelings for the playboy, Haneji cut all ties after graduation. But now that Aragaki has found him, he has no intention of letting Haneji go...