A colleague of Xu Chenghuai at the research institute, referred to as Uncle Ma by the children and Old Xu by others. He is more sociable and joking compared to Xu Chenghuai. He once mediated during an incident when Yunkai accidentally injured someone while racing motorcycles, when Xu Chenghuai was away on assignment. After that incident, Yunkai became extremely hostile toward Ma Yuanhang's son Ma Fenghuo, despite the two boys having been close childhood friends.
