Garuru is an S-rank sniper and leader of the Garuru Platoon—and Giroro's older brother. He's an indigo Keronian with a black helmet, a downward-pointing red triangle as his symbol, and a belt designed for raw power (unlike Giroro's memorial belt).
When word reached him that the Keroro Platoon was getting nowhere with their invasion mission, Garuru decided to handle things himself. He showed up on Pekopon, initially beat Giroro one-on-one, but lost the rematch when the Keroro Platoon rallied together. It's strongly implied his real goal was just to test their abilities anyway.
Garuru pops up occasionally after that. In episode 130 he faces a Giroro clone, and later helps the platoon take down a creature called ZZZ—he's apparently the only one who can say its name without mangling it. He also shows up in the manga pretty regularly. One story has him arriving on holiday with a "gift" that transforms into a giant flying sweet potato, which turns out to be their father's way of teaching the brothers a lesson. They need backup to bring it down, and Natsumi in her Powered form actually impresses him by taking it out with her beam sabers when guns prove useless.
There's a flashback in that same arc showing teenage Garuru defending a young Giroro and a friend from bullies at their secret hideout. Interestingly, younger Garuru wore a belt like Giroro's current one—rectangular buckle and all. By volume 15, he's sending Pururu to check in on the Keroro Platoon's invasion efforts.
Content compiled by AnimeList.moe from publicly available sources.
