Taro Achi is a Japanese light novelist and screenwriter born on October 3, 1980, in Nagano Prefecture. He began his career while still a high school student, winning the Silver Prize in the fourth Dengeki Novel Prize for his work Boku no Chi o Suwanaide. Following his graduation, he traveled abroad for several years before returning to Japan to pursue writing full-time. Achi is also a member of Red Entertainment, where he works as a scenarist.

Achi gained significant recognition for creating the light novel series Sumeba Miyako no Cosmos-sō, which was later adapted into the manga and anime franchise known internationally as Dokkoida?!. The original light novels, illustrated by Yu Yagami, were serialized by ASCII Media Works from 1999 to 2003. The story follows Suzuo Sakurazaki, an unemployed young man hired by a space alien to test a powerful suit under the guise of a toy company, leading to a series of comedic confrontations with rival intergalactic corporations. The manga adaptation, co-authored with Yu Yagami, was published in Dengeki Comic Gao! and later licensed for English release by CMX Manga under the title Dokkoida?!. An anime adaptation produced by ufotable aired in 2003, which was subsequently licensed for North American distribution by Geneon Entertainment and later by Sentai Filmworks.

His other major work is the series Kage Kara Mamoru!, known in English as Guardian Ninja Mamoru or Mamoru the Shadow Protector. The original light novel series, illustrated by Sai Madara, was published by Media Factory's MF Bunko J imprint from July 2003 to March 2008, spanning twelve volumes, and was followed by a sequel series titled Motto! Kage Kara Mamoru! beginning in July 2009. The story centers on Mamoru Kagemori, a high school student from a family of ninjas sworn to protect their neighbor, the clumsy Yūna Konnyaku, a duty that has continued for four hundred years. A manga adaptation, also written by Achi and illustrated by Sai Madara, was serialized in Monthly Comic Flapper and Monthly Comic Alive. An anime television series co-produced by Group TAC and Aniplex aired on TV Tokyo in 2006. The manga was published in English by DrMaster as Mamoru the Shadow Protector, and the anime was later licensed by Sentai Filmworks.

Achi’s creative identity is characterized by a blend of comedy and science fiction or fantasy elements. His notable works frequently involve ordinary young men thrust into extraordinary circumstances, such as testing alien power suits or upholding ancient ninja oaths, with a strong emphasis on humor and character-driven situations. Beyond his work in light novels and manga, Achi has also contributed as a writer for video games, with a credit on the 2019 title Our World Is Ended.