Maliik is referring to an event in the first Astronaut Academy book, where he was saved by Miyumi San during a robot invasion/anti-gravity drill. She disappeared before he could find out her name, but has been obsessed with her ever since. Maliik believes he and Miyumi must share a special connection because they were both wearing similar striped shirts on the fateful day they crossed paths.
The kid with the glasses and swooshy hair is Marcos Stamatis, who will get his own chapter later in the story.