I don't know if it's incomplte in Japance but to be honest with you 100% it say's on information site's 2 volumes so i say it's complete on there end just not our's when can buy it but all in there language unless your willing to lear japanecse LOL
OH it's from " Sekaiichi Hatsukoi "
https://www.mangago.me/r/l_search/?name=world+greatest+first+love
https://myanimelist.net/anime/9926/Sekaiichi_Hatsukoi
It's there both there first & last name's together (▰˘◡˘▰) they are the one's that i have as my profile picture and are on the cover of the manga if you have not seen the anime i recommend it very hightly !!!
It has a OVA , movie and a spin off !!! ヾ(☆▽☆)
YES!! Actually your name pleasantly surprised me because Sekaiichi is my very first bl. A story i fell in love with and that i still carry in my heart. Remember when people used to say Sekaiichi was going to end after Onoders would confess? Haha i never believed it would because there were so many things to unpack still, and here we go it's still ongoing. The translation upload here in the site is so goddamn slow but it's still being updated nonetheless!! And yes i also saw the anime
No because like i said i stop and wanted to wait till it was completed but it was taken year's so i broght the first 4 voulumes and there were " i love you's in it " yes i know Takano never heard them because Ritsu was wipering it or something but they were still confesing's with him no matter what but Takano always new that Ritsu loved him no matter what and i don't know how well you remember the anime or how many time's you have seen it but in high scool they never broke up at all !!!
Ritsu transfred to another schoo through a misunderstanding about Takano when they were in his room together

to voulomes completed this really need's to be picked up !!! this came out before i belive in 2010 when the author completed this but as for the person / people that translate this nothing and now years later still no one has picked this awesome manga up :/ (╬ ̄皿 ̄)凸