is a Japanese light novel author and the original creator of the Toaru Majutsu no Index light novel series and its spin-off manga series, Toaru Kagaku no Railgun and Toaru Kagaku no Accelerator. He also actively works on the manga and anime adaptations of both Index and Railgun, and has worked on other related media such the original plot of the PSP games.
As he uses a pen name, his real name and identity is as of yet unknown.
Before becoming the famous writer of the Index light novel series, Kamachi wrote a story entitled Schrödinger's City (シュレディンガーの街 Shuredingā no Machi?) as an entry in the 9th Dengeki Game Novel Prize; unfortunately, his submission failed to reach past the third selection stage of the said competition. However, his story caught the attention of the editor-in-chief of Dengeki, and Kamachi later becomes in-charge in writing the book Kaite-minai ka? (書いてみないか？? lit., Want to Try Writing?), which becomes his debut as a professional writer.
Kamachi's identity has been shrouded in mystery. He has little to no media exposure, and like many novelists, uses an avatar — a face created from simple shapes like circles or oblongs — as a picture in his publications, often describing himself as "a new author hoping to take the most unmotivated author picture in the world" as a self-introduction in his debut work. Haimura Kiyotaka, the illustrator of the Toaru Majutsu no Index light novels has once thought of him as "delicately sports-minded", while the author of the Toradora! light novels, Takemiya Yuyuko, upon meeting the author personally, was surprised to discover him as "younger than expected".
Kamachi began writing novels while he was still studying as a junior high school student. However, his works were not finished until he graduated from high school.
Kamachi considers writing novels as his pastime, and he takes joy in doing so; in fact, he is noted for his very quick pace of writing. This exemplified by volume 2 of the Index novels which was written at the behest of his editor, and was forced to complete it in 17 days. He is also extremely prolific, apparently managing to write for two of his light novel series on schedule, and at the same time writing for other side projects. Indeed, even Kazuma Miki, editor of the Toaru Majutsu no Index novels, has noted the amount of output he has in his autobiography.
On holidays, he plans on the progress on the plot and prepares manuscripts. Kamachi also takes some time to research on materials for the light novels.