James Asmussen is an older man who works in the stables at Winfeed, where he is responsible for the care of the horses. His many years of experience with both jousting and horses have granted him keen observational skills, allowing him to occasionally offer precise and valuable advice to the knights and their attendants. Because of this, he enjoys a great deal of trust among the students, and he is considered by the protagonist Takahiro Mizuno to be an excellent counselor. Asmussen himself believes that Takahiro resembles his own younger self, and he offers him guidance in all routes of the story. When Takahiro begins a romantic relationship with someone, Asmussen offers him kind words of support, acting very much like a benevolent grandfather and showing particular care for him.

Beyond his work in the stables, James Asmussen enjoys playing chess. He occasionally plays matches with Kyle or Lisa Eostre, though his skill level has not improved much and is said to be roughly on par with Kyle's. He is also revealed to be a close friend of Ayako Hiiragi's grandfather, with whom he enjoyed discussing horses and jousting while sharing drinks. On that occasion, it is also shown that Takahiro Mizuno had known about the friendship between the two older men for some time.