Race: Moon RabbitAbilities: Lunacy-inducing eyes, telepathy with other moon rabbits, manipulation of wavelengths
Age: Unknown, at least 38 years old
Occupation: Kaguya's pet and Eirin's Student as medicine seller at Human Village
Location: Eientei
Reisen is one of the legendary rabbit months, he escaped from the Moon to the Earth as a refugee from "Lunar Wars" between two worlds which began in 1969 AD after the invasions of Apollo 11 "". Make a trip to Gensokyo he is surprised to meet the famous fugitive Kaguya and Eirin, and asked for asylum in Eientei. Instead, he worked for and protect Kaguya and Eirin.
During the night hiding in a lasting Reisen Eientei to avoid a possible lunar envoy arrives on Earth and forced him to return to the Moon. He served with a sealed entrance Eientei to ensure that Kaguya can not be found by the delegates well. He uses his power to stop the hero from the madness of attacking Eientei, but was defeated. Reisen power of the madness comes from his eyes, he uses it to deflect and twist waves, confusing and confused victims and deceive them with the illusion scary.
Perhaps ironically given his power mad-inducing, Reisen seem to have one of the more stable and balanced personality in Gensokyo. In Phantasmgoria Flowers Look at him worried about Tewi vague and seems to level more than most other characters. Although he did not know what caused the incident rate, he decided to investigate by going to wherever the flowers are blooming.
During the events in Scarlet Weather Rapsody he appeared in the Scarlet Devil Mansion to ask questions but was beaten by Mrs. angry. Then he asks the fate of the Temple Hakurei and asked whether the earthquake was still happening. Failing to find clues, he then went to Hakugyokurou to check the condition and asked about the destruction of the Temple's Yuyuko. He told me about the ceremony was over "" the new sanctuary, but when he went there, the temple was destroyed. He also met Yukari, who forbade him to investigate the shrine. Some time after the battle with Yukari, Tenshi suddenly appeared and said that the earthquake Reisen only "good."
Also, Silent Sinner in Blue, the previous owners, the Sisters Watatsuki, others ReisenII Month rabbit named after him.