Both movies are set in the deep Japanese countryside in the middle of the 20th century. Both capture the playful innocence group of children in a realistic portrayal, not idealized cartoon kids. Both mix in drama and a historical plot. Both manage to create the bittersweet emotion of fleeting happiness the Japanese call "mono no aware". On a technical level, the art design is strikingly similar. Omoide is by Studio Ghibli, and Mai Mai by Madhouse but both share the "Ghibli-esque" vibes, where Mai Mai surpasses some of the lesser Ghibli films actually.
