Ichiro Mihara (三原 一郎 Mihara Ichirō?) nicknames himself Icchan (いっちゃん) to hide his true identity from Misaki Suzuhara. He is 28 years old and oftens acts eccentric, spontaneous, and immature for his age. He often jumps out of random places, shouting "Icchan go BOOM!", to scare Misaki and Masaharu Ogata. He is ingenious and dead serious when it comes to Angelic Layer. In the manga, Icchan is the president of the Piffle Company, creators of the Angelic Layer toys. In the anime, Icchan is the "father" and creator of Angelic Layer, having developed the game over seven years with the help of Shuko Suzuhara. Icchan was an employee at a hospital that was trying to treat Shuko's neurological condition. They were developing the angels as part of their research into creating prosthetic limbs which could be controlled by brain waves. When the research funding was cut off, Icchan and Shuko created Angelic Layer in order to help fund further research.
According to volumes 7 and 8 of the Chobits manga, it is heavily implied that Icchan is the late husband of Chitose Hibiya and the creator of the persocoms. Since he and Hibiya could not have children, he made two special persocoms, the Chobits, to be their children. They were named Freya and Elda (later known as Chi). The Chobits were created using information gathered from the research performed for the Angelic Layer project. In the Chobits anime, Icchan only appears in one scene but is not explicitly named.
In a letter on Clamp's website about Mugen no Yami - echo of the past, Clamp mentioned their "long time friend Ichirou Mihara", who is the vice president of the video-game company Arika, so this is most likely the source of the character's name.