If you're looking for manga similar to Petit Gargantia: Special Project, you might like these titles.
This is a story that takes place in a certain prefecture in the north. In contrast to the few daylight hours it gets, its people are cheerful if a bit eccentric. Among them is Akita, a horned girl. A naturally argumentative and positive child, she lives happily every day. Spicing up her life is Asahi, her slightly odd childhood friend, and Komachi, a city girl who isn't quite used to life in the prefecture yet. There's also Akita's older sister, a member of the Girl Scouts.
Ai-chan is the AI system for Honkai Impact 3's battleship, [Hyperion]. She's in charge of operational tasks such as training new cadets, commanding the battleship, and analyzing data. She's the "real" main character... ?!?! Here comes the facts that Honkai Cutie Ai-chan would never tell to players!
An official gag comic for the TV anime, "KIZNAIVER" appears! In this gag comic, all of the "KIZNAIVER" characters have turned mini, and live out unbelievable days in Sugomori City. You get to enjoy a slightly different story from the original.
Dr. Einstein identified a world-ending phenomenon known as the Vodka Girls. Dr. Tesla has been dispatched to end their cataclysmic spree across the multiverse. Will she succeed?