Melody of Memory and KH3 remind. Spoilers ahead.

remind starts one year after the ending. Haven’t seen remind in a while, but everyone was looking for Sora, with the “Twilight Town gang” (Roxas, Xion, Lea, etc) looking for clues there, while the Birth By Sleep gang went into the realm of darkness. Riku and the group of Radiant Garden/Final Fantasy characters looked through a Data Sora (hence the remind data battles). Kairi was asleep for a year while Ansem(?) and the other group (names slipped out of my mind) searched through her memory. They end up finding out about Quadratum, sent for every other previously mentioned group to stop their search, and had Riku travel to Quadratum. This is where KH4 starts.