Taihei Doma (土間大平 Doma Taihei?) is the deuteragonist of the Himouto Umaru-Chan! series and the main protagonist of Himouto! Umaru-Chan: Himouto Ikusei Keikaku visual novel game. He is the older brother of Umaru Doma who works at a company.
Taihei is a young man of average build, appearing fairly slim and with pale skin. He has shaggy, straight black hair with a noticeably sharp, pointed strand at the top of his head. His eyes are colored brown, just like his sister.
Taihei is most often seen wearing his work uniform which consists of a black suit with a blue striped tie, a white undershirt, black shoes, and his usual glasses.
Taihei can also been seen wearing a variety of outfits common to young men such as himself like jeans, button-up shirts, t-shirts, etc. He also occasionally wears a blue apron when cooking for Umaru.
Taihei is a kind and hard-working person who loves to cook. He is well known for being a pushover and excessively tolerant of other people slacking off, such as Umaru Doma or his co-worker, Takeshi Motoba.
Taihei, while polite and well balanced, is described as a bit of a doormat, as his younger sister constantly relies on him, making him cook, clean, buy, and do whatever she tells him to. Though Umaru may be unbearable at times, Taihei appears to deeply care for his sister and worries about her future as an independent person, admitting that he has spoiled her for too long. Although Taihei does internally express anger towards Umaru during her more unbearable moments, he often calms down and tries to take a friendlier approach to winning her happiness back, which he always succeeds in doing.
At times, Taihei seems to have trouble with remembering certain things in his past, a result of a possible long-term memory deficiency. Umaru seems to take the place in his mind of the people he has forgotten.
Taihei is often gullible and is easily duped into doing whatever Umaru tells him to, especially in the presence of peer pressure, which he is extremely sensitive to. In one instance, she made him miss work so he could help her win a Necolumbus, covering up her motive by convincing him to use that time as a form of relaxation when in actuality, she tricked him into helping her and improve her odds of winning.
Even though he seems very sensitive to other people's feelings, he has also shown to be especially oblivious to others' love interests, as shown when he does not realize both Kanau Kongo and Nana Ebina have feelings for him.
It is known that Taihei had been living in his residential area for a long time as he remembered walking home from school with his mother when he was small. Considering his father is extremely wealthy, his mother was presumably a mistress.
Taihei has been in his apartment for at least a year as he noted that Umaru Doma had moved in with him about a year ago.
- The name Taihei means "big, great" (大) (tai) and "flat, broad, level, even, peaceful" (平) (hei).
- Taihei's surname Doma means "dirt floor" (土間).
- In high school, Taihei was known as Demon Taihei because of how pointy his hair is and because he got perfect scores all the times, just like Umaru Doma.
- Taihei loves cats, as seen in Episode 7, and he even dreamt of petting them.
- Taihei is afraid of driving vehicles.
- Umaru greatly resembles the siblings' mother, which might explain why he is extremely tolerant of Umaru and her strange habits or behavior most of the time.
- Taihei works for Diamond Service.
- Taihei has a dislike for chocolates and anime.
- When playing the "Game of Life", Nana Ebina and Taihei married in-game and they supposedly had three children.