The stereotypical computer nerd, Yaegashi does computer analogy for the TAC. On off days, he enjoys hentai games on his computer. He also has a program that pinpoints the Aragami's weak points and attacks, but it doubles as a program to predict what animal would appear on Momiji's panties. He has a love/hate relationship with Kome through most of the series.
Daitetsu, or Mr. Kunikida, is the Chief Director of the TAC. When Kaede and Momiji were born, Mr. Kunikida raised Kaede like his own daughter, but he exploited her ability to track down and kill the Aragami. However, when Kaede sacrificed herself, he felt heartbroken. With Momiji in the TAC, Mr. Kunikida decides not to exploit her abilities like he did with Kaede and instead treated her like a normal girl. Source: Wikipedia
A moon rabbit, she came to Gensokyo about 30 years ago to escape a war between the Earth and the Moon. Since then, she has been an apprentice to Eirin, a pet to Kaguya, and a caretaker to Tewi. She has the power to drive people mad with her eyes — mainly in the form of hallucinations — as well as communicate telepathically with her kind. She also has control over waves of all kinds, such as light waves, brainwaves, and electromagnetic waves. "Udongein" and "Inaba" are both nicknames, the first given her by Eirin and the second Kaguya; the latter is what Kaguya calls all rabbits. (Source: Wikipedia)
After taking good care of her health and living for a long time, Tewi became something more than an ordinary rabbit. She leads the Earthborn rabbits living in Eientei. Her impetuous temperament makes her seem more like a fairy than a phantom. Humans who lose their way in the bamboo forest around Eientei sometimes catch a glimpse of Tewi. Those who see her are able to find their way out without fail, so she is considered a guide of the forest. It's a shame that they waste the fortune given to them by Tewi on such a small thing, but humans are too clueless to notice their mistake. (Source: Touhou Wikia)
A witch who has settled down in the Scarlet Devil Mansion. Unlike the mistress of the house, she is not weak against sunlight; however, she does not go out much. She spends her days in a library where the sunlight cannot reach. This is so that the books won't be damaged, but the unhealthy atmosphere is bad for her health. She doesn't have a very proactive personality, but rather always walks her own path. However, she is always interested where knowledge is concerned and will proactively go and try to acquire it. She completely depends on her books, but still makes a lot of mistakes. Although she is quite skillful, her complete lack of physical fighting ability can't be helped. She pretty much never attempts to directly punch or kick her opponent. She makes up for this with her knowledge of a great variety of powerful magic. She's more at ease using magic than trying to attack physically. Dividing the magic she uses according to the days of the week is a secret hobby of hers, but no one has realized this. (Source: TouhouWiki)
A former member of Tokyo Metropolitan Police, Ryoko uses her police instincts to help the TAC. Ryoko uses her standard police issue weapons in conjunction with weapons modified to be used against the Aragami. She is in love with Kunikida. Source: Wikipedia