What about DxD and Tensura?.
Hope these will be the harem of the franxx book: Zero Two (obviously), Miku, Kokoro, Ikuno & Ichigo.
Have you read the Franxx manga it is acctually kind of better then the anime in some regards.
I just realized when washing dishes at work today that Darling in the Franxx and Attack on Titan have the same type of ending
1. The main character/characters turn into a giant being to defeat an opposing force and protect their friends.
2. The resting place of the main character or second main character in Zero Two's case is at a tree.
3. We see the tree grow bigger and older as the city expands and grow's into a futuristic state.
4. The end show's a kid/kids at/discovering the same tree.
Wouldn't you agree that Episode 15 of Franxx should have been the ending of season 1 and the second revolves around setting up VIRM as the antagonist.