Before starting dating Minato Kushina had a threesome with Fugaku and Mikoto, during that night Fugaku was able to impregnate Kushina with Menma and Mikoto with Itachi.
Years later Menma is living with his younger half brothers Naruto and Sasuke and his widow mothers Mikoto and Kushina.
Both Naruto and Sasuke have their own goals, Naruto wants to become the Hokage and Sasuke wants to kill Itachi.
So Menma also decides to have his own goal, and that to restore both the Uzumaki and Uchiha clan in one clan, and the first woman to become part of his harem is Kushina because she is the only pure-blood Uzumaki in Konoha.
Menma looks the same is Menma from RTN Movie.
Some of Menma's girls:
Kushina: his main wife in the harem and the one that help him add more wives into his harem.
Mikoto: after a threesome with Menma and Kushina she becomes part of the harem.
Hinata: a shy girl that has a crush on Naruto, but Menma able to steal her and after speeding time in Menma's bed Hinata turns from the shy girl into the RTN Hinata.
Tsunade and Shizune: Tsunade owes Menma a lot of money, so Menma uses this to make both Tsunade and Shizune have sex with him until they become part of his harem willingly.
Kurenai, Anko and Yūgao: all of three of them were part of Kushina's team, so she is able to convince them into joining her into Menma's harem.
Tsume and Hana: Menma able to seduce Tsume, but he also wants a threesome, so Tsume makes her daughter join them.
Temari: because Sand Village attacked Konoha with Orochimaru Tsunade the Hokage forced them to give Temari to Konoha if they want peace, because of this Temari becomes part of Menma's harem.
