Darling in the Franxx
Humanity is being attacked by monsters called klaxosaurs. After humanity was almost completely destroyed, an organisation called APE moved humans to cities called Plantations. Children called parasites are used to defend the plantations. They use large mecha called Franxx in pairs. Adults cannot die and they live in the Plantations. They don't make babies or make relationships anymore. The children are created artificially. They are only taught to pilot the Franxx.