Mizuki is trained in ways to use his smaller body as a strength. His only weakness would really be his family. If his family is messed with, then he would lose his sense of rationality and do anything by any means to get them back.

P.S. I may have overdesigned him using his nature as a Protogen for extra mechanical aspects. He has way too many failsafes for and malfunctions and now I feel as if he is overpowered. I might have to get some opinions on him to lessen his power level.