Mobile Suit Gundam: Iron-Blooded Orphans (2015)

The Gundam series that puts child soldiers front and center. On a terraformed Mars, orphaned boys hired out by a security company turn on the adults who treat them as expendable, refound it as the mercenary company Tekkadan under Orga Itsuka, and fight with an old Gundam, Barbatos, piloted by Mikazuki Augus. It runs on its own Post Disaster calendar, so no knowledge of the 1979 original is needed, and it takes on war, slavery and child soldiers directly. Sunrise made 50 episodes over two seasons from 2015 to 2017, directed by Tatsuyuki Nagai and written by Mari Okada. The second season ends hard, so go in ready for that.