Yuyuko is the ghost 'princess' of Hakugyokurou, the netherworld of the "formerly-living," but was once a living human. Long ago, after her death from suicide, her body was used to place a seal on the Saigyou Ayakashi, a dangerous youkai cherry tree, to stop it from killing innocent humans. During the events of Perfect Cherry Blossom, she enlisted Youmu to find a way to make the tree bloom to resurrect the corpse buried beneath it, apparently unaware that it was her own body. Forced to abandon her plan as it would only result in her own destruction and the unleashing of the Saigyou Ayakashi's terror once again, she resigned herself to continuing the existence she had been fated to. She has the power to invite mortal souls to death, and those souls who perish this way wind up in Hakugyokurou rather than heaven or hell. Though it might seem dangerous for such a whimsical, flaky personality to wield such a terrible power, Yuyuko has an immense sense of responsibility regarding her power, and never uses it recklessly or out of spite, nor does she use it as a weapon. Ironically it was this power that drove her to kill herself in the first place. Humans fear Yuyuko because of her awesome power and a general fear of the supernatural, but she is very cheerful and friendly. Unlike many ghosts she resembles a living human, and her playful, good-humored personality has a disarming effect. She often makes bizarre and nonsensical remarks and sometimes seems to overlook the obvious, leading to her characterization as an airhead or ditz. However, at other times she can be extremely cunning and perceptive and has a vast amount of knowledge; it is not known whether it is the ditzy side or the smart side that is her true personality. She seems to never take anything too seriously, and loves to tease her straight-laced assistant, Youmu, whom is her opposite in almost every way. She is also known for her incredible appetite and seems to have a food-related metaphor for any situation. Yuyuko is truly "dead and loving it." (Source: Touhou Wiki)
A member of "mecha mecha mote te ru mondaiji sannin gumi" or MM3. He is a bit ecchi and likes sweets.
Kaji is in the same grade as Ayu and Nina, and is also the school idol. He is considered cool and always has a nice smile. All his fans are constantly giving him presents, and he even has admirers from the 3rd grade. However, this is only his outer mask. Kaji is in reality a normal guy who hates being given presents by people he doesn't know. But he is working hard on his "nice person" persona because the girl he likes, Ayu, once told him that's the way she liked him. He becomes closer to Nina after she discovers his deception. He is an introverted person, and doesn't like giving away his real feelings or thoughts. Kaji belongs to the school's baseball club. His best friend is Tsujiai.
Tsujiai is a classmate of Kaji, Ayu and Nina. He is the head of the male tennis club and is a slightly extravagant person. Ayu seems to hate him because at the start, he always managed to destroy her chances with Kaji one way or another. Tsujiai introduces Nina to Doraemon (which she loves). His best friend is Kaji and he likes Nina which is shown more in the manga than in the anime. He has a cat name Shinnosuke and is the third person to know that Nina was a magic girl because he saw that Rio the cat transforms into a human.
Gouzu and his brother Meizu formed the Demon Brothers. They were hired by Gato to kill the Bridge Builder Tazuna, and therefor stoping the work on the bridge from the Land of Waves, making all of the Wave Country's citizens lose all their hope. They bothy attacked Tazuna, who was guarded by Team 7. After a little quick battle, they were tied up to a tree and left there. The Demon brothers are a paragon of coordination attacking. Their large metal gauntlets house a retractable shuriken chain running between the two of them, which they can use to bind an enemy and then slice them to pieces. In the event that the shuriken chain is neutralized, they also have a release mechanism, to free them up for individual attacks. They use the sharp, poisoned claws on their gauntlets to shred their foes. As Kirigakure Chunin, they are renowned for their fighting resolve.
Dengaku is a food stand merchant in the Fire Country who sells a variety of things. His stand was where Tsunade drank sake with Jiraiya before she met with Orochimaru.
Ami (亜美) was an Academy Student from Konohagakure. She appears during a flashback to Ino Yamanaka and Sakura Haruno's time in the Ninja Academy. During a kunoichi lesson she taunts Sakura about her forehead, prompting Ino to throw a flower (that she claims is poisonous) into Ami's open mouth. Ami quickly runs away to tell their teacher, Suzume. She has purple hair in a style similar to that of Karin. (Source: Narutopedia)