Doronpa is an Obake, a type of ghost or supernatural being, who originates from Texas in the United States. Prior to coming to Japan, he lived in a squire's house. His physical appearance is distinct, featuring a light pink body with properly divided legs, a detail that differentiates him from the main character Q-Taro. The most notable aspect of his appearance is a large, detachable red star on his stomach, which serves as the source of his Obake powers; beneath this star is a pattern of stars and stripes that symbolizes his American heritage. His favorite food is hamburgers.

In terms of personality, Doronpa is characterized as being intelligent and possessing good motor skills, but he is also playful and mischievous. He enjoys playing pranks not only on Q-Taro but also on neighborhood children and even the elderly human with whom he lives. He has a tendency to exploit his abilities to annoy and mock Q-Taro, often treating him as an inferior due to his pride in being American, which leads him to make comments that implicitly disparage Japanese culture. Despite this antagonistic exterior, Doronpa is often quite lonely and is, deep down, kind-hearted. This softer side allows him to form a genuine connection with his human companion, Kaminari, who is also referred to as Mr. Kamisei. He has a sentimental side and can become depressed when he is severely scolded for the trouble he causes.

Doronpa's primary role in the story is that of a rival and bad friend to Q-Taro. Their relationship is defined by frequent quarrels and competition. This rivalry is partly fueled by the fact that U-ko, a female Obake who is Q-Taro's girlfriend, idolizes Doronpa's intelligence, which in turn sparks Q-Taro's jealousy. Another significant motivation for Doronpa is his fondness for P-ko, who is Q-Taro's younger sister. He has a crush on her and wishes to date her, but his attempts are consistently interrupted and thwarted by a protective Q-Taro. Despite this, there are indications that P-ko may return his affection, as they are sometimes able to go on dates.

While his relationship with Q-Taro is contentious, he maintains amicable friendships with other human characters like Shota and other Obake such as O-jiro, U-ko, Godzilla, Hakase, and Kizao. Interestingly, unlike most Obake in the series who are terrified of dogs, Doronpa has no such fear and has even been known to use dogs to torment Q-Taro. He also seems to enjoy being in high places, often appearing on rooftops or in trees to take naps.

Throughout the story, moments of character development reveal the complexity beneath his mischievous nature. He has demonstrated a capacity for consideration, such as temporarily assuming Q-Taro's form to maintain a presence among their human friends when Q-Taro was away, showing that he does care for others. On other occasions, however, he can act with shameless indifference when his pranks get others into trouble. As an Obake, Doronpa possesses several notable supernatural abilities. He can fly, become invisible, and has advanced transformation skills, allowing him to shapeshift into various objects and people. He frequently uses this transformation ability to impersonate Q-Taro and cause mischief. This power is a key point of contrast with Q-Taro, who cannot transform. However, Doronpa's abilities are dependent on the red star on his chest; if it is detached, he is unable to use his powers.