Arina: "Nachi: The vocalist of the male duo OZ. (I once wrote that they were a band but that's a mistake) In the side story it was revealed that he was a rich kid from Kyoto, he's Madoka-chan's fiance, and that he had plastic surgery to become a singer to chase Madoka-chan. Whenever he appeared almost all the fan letters and emails to the Ribon website went to were for Nachi-kun. I was really worried about Takuto's popularity. His hair color is green. Madoka-yan's hair is purple. Oh no! It's the same as Jeanne's Minazuki-kun and Miyako-chan!! And I created them! (sweat) I draw him without thinking. So he's really easy to draw. I think he has this natural aura. I nicknamed him "Natchii." When I was talking about Natchi of morning of Morning Musume at a meeting, my editor thought I was talking about Nachi-kun. It was confusing, but even that's a good memory now."
Souichirou "Nachi" Shidou is Madoka`s Fiance, who appears in various volumes in Full Moon Wo Sagashite. He changed his name to Nachi after getting plastic surgery because he was tired of being called "Cheesy" by Madoka. In one chapter of Full Moon, Nachi was knifed shortly after an incident involving Ms. Oshige and a birthday present for Mitsuki. In the seventh volume, Nachi and Madoka can be seen on a balcony watching Mitsuki`s performance. He is also a servant of a prince.
The above information was copied directly from Full Moon Wo Sagashite by Arina Tanemura, Manga Version obviously, since Nachi was never in the Anime.