Xiaoyu Lei is a former member of the Heilei who currently serves the Shinoyama Clan. His ongoing assignment is to protect Sayo Shinoyama during her residence with the impostor posing as her half uncle. When introduced, Xiaoyu presents himself as capable, eager-to-please, and humble. Underneath that pleasant demeanor, however, lies murderous intent toward both the Polka impostor and the real Polka Shinoyama. With the former, he presumes the impostor is an inherent threat to the Shinoyama family. His latter grudge against Polka is meanwhile rooted in his own filial worship of Rozan Shinoyama, as he has long been jealous of Polka for being the subject of Rozan's fatherly affections. Over the years, his resentment has evolved into a superior complex wherein he believes he the truly useful son to Rozan and more deserving of the role than the inferior Polka.

Xiaoyu can be extremely stubborn in his suspicions and convictions, intent on doubting if not assuming the worst of the fake Polka even after Rozan says he trusts the impostor. Such stubbornness stems from his personal jealousies and his extreme devotion to the Shinoyamas, both feeding into his need to prove himself as an ideal bodyguard, servant, and 'son'. He is proactive in his goals and extremely suspicious to intense and sometimes comical effect, considering his eavesdropping and frequent late-night activities. To Xiaoyu's credit, his pride and self-confidence allow him to stand his ground against the Heilei and openly reject his blood family.

(Source: Dead Mount Death Play Wiki)