Atsuhiro's Quirk allows him to "compress" anything in a spherical area into a small marble without actually damaging it. To activate it, Atsuhiro needs to touch the target with his hand, even through his glove. The weight of the compressed objects is reduced considerably, making it possible to carry them in one's pockets or even in one's mouth. It appears this Quirk can be used in absolute stealth, without noise and before the victim can attract the attention of nearby allies.
If used on a person, it effectively entraps them, terminating the fight in an instant and allowing Atsuhiro to abduct them easily. This is particularly useful against opponents who are resistent to certain forms of attack, such as Snatch. However, if he focuses on an area smaller than the target's whole body, he can compress only certain parts of their body, mutilating them. Atsuhiro's compression also extends to inorganic entities, as he has been shown pocketing away pieces of Shoto Todoroki's ice and dig holes underground by carving away earth.
Atsuhiro can release a single marble by wishing it, or all of them at the same time by snapping his fingers. This can come in handy to lay traps, which he demonstrated by throwing a marble under a police car and releasing his Quirk, causing the rock he had "compressed" to instantly recover its original size and launch the car upwards. Atsuhiro can also use the Quirk on himself to avoid an attack and then disengage it right afterwards.
- Compression - Wikipedia article about the general effect caused by Atsuhiro's Quirk.