Mitsuru Adachi is a Japanese manga artist born on February 9, 1951, in Gunma Prefecture. After graduating from high school in 1969, he moved to Tokyo and worked as an assistant to manga artist Isami Ishii. Adachi made his professional debut in 1970 with Kieta Bakuon, which was published in Deluxe Shōnen Sunday. He modeled the spelling of his family name, using the hiragana "あだち" instead of the kanji "安達," after the example of his older brother, who was also a manga artist.

Adachi is widely known for creating original manga series that blend romantic comedy with sports, particularly baseball. His first original series was Nine, serialized from 1978 to 1980. He followed this with Hiatari Ryōkō! from 1979 to 1981 and Miyuki from 1980 to 1984. His breakout work, Touch, ran from 1981 to 1986 and became a defining title of his career. Other notable original works include the swimming-themed Rough, the baseball epic H2, the boxing story Katsu!, and Cross Game. In 2012, he began Mix, a semi-sequel to Touch set thirty years later.

Many of Adachi's original manga have been adapted into anime and live-action productions. Nine was adapted into multiple films beginning in 1983. Miyuki received an anime television series and a live-action film in 1983. Hiatari Ryōkō! was first adapted into a live-action TV drama in 1982, and later into a 48-episode anime series in 1988. Touch was adapted into an anime television series that aired from 1985 to 1987 and became one of the highest-rated anime programs in Japanese history. Slow Step was adapted into a five-episode original video animation in 1991. H2 received a 41-episode anime television series in 1995, and Cross Game was adapted into an anime that began airing in 2009. Mix received an anime adaptation that began in 2019.

Recurring themes in Adachi's work include youth, first love, friendship, and the pursuit of the national high school baseball tournament at Koshien. His stories are often described as love stories disguised as sports manga, emphasizing character development and quiet, emotional moments over intense athletic competition. His narrative style makes frequent use of subtlety, suggestion, and what is left unsaid. A notable characteristic of his plots is the frequent occurrence of tragic accidents or sudden deaths that profoundly affect the protagonists, such as a key character dying in a traffic accident in Touch or drowning in Cross Game. His art style is clean and recognizable, though he has occasionally acknowledged the similarity of his character designs across different series.

Adachi holds significant stature in the manga industry. He is one of the few artists to have written successful series for shonen, shojo, and seinen manga magazines. He won the Shogakukan Manga Award in 1983 for both Touch and Miyuki, and again in 2009 for Cross Game. His works have sold over 200 million copies, and in 2008, Weekly Shōnen Sunday devoted an entire issue to him and his work in recognition of this achievement. He has been praised by critics as a master storyteller and a genius at portraying everyday life.