 If you liked
Qko-chan
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 ...then you might like
Narutaru: Mukuro Naru Hoshi Tama Taru Ko
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Similar themes:
An extraterrestrial lifeform (Aliens in Qko-chan and Dragons in Narutaru) lands on earth,The Main protagonists are kids or young teens that met extraterrestrial creatures that they pilot or ride to fight on the war,Emotionally unstable kids,The military is creating plans to fight the aliens and win the war(Although, in Narutaru, Humans are controlling the Aliens), Adults showing no mercy to children (they don't mind hurting children),and many more..
Qko-chan is a bit less violent to Narutaru though.