Seishun no After
青春のアフター, 청춘의 애프터; 青春过后; After of youth
Author & artist: Midori No Rupe (緑のルーペ, Midori no Ruupe, 미도리노 루페)
Makoto Toba hates everyone in his class. Everyone except, Sakura Touwa, an introverted high school girl who lives with her grandma and loves video games. But one day, Sakura disappears right in front of Makoto? Makoto has visited the site of her disappearance on the anniversary of her disappearance for the last 16 years. That is, until Sakura comes back from the time slip she was stuck in, and to her not a moment has passed. Now at 32 with a girlfriend, Makoto has to take care of his 16-year-old childhood crush. What could possibly go wrong?
English
https://mangakakalot.com/manga/en924236
Japanese (日本語; にほんご)
https://raw.senmanga.com/Seishun-no-After
http://rawlh.com/manga-seishun-no-after-raw.html
Korean
https://jmana.net/book/%EC%B2%AD%EC%B6%98%EC%9D%98%20%EC%95%A0%ED%94%84%ED%84%B0
https://manamoa29.net/bbs/page.php?hid=manga_detail&manga_id=1253