Hiroyuki Asada is a Japanese manga artist and illustrator born on February 15, 1968, in Yokohama, Kanagawa Prefecture. He made his professional debut in 1986 with the short story Hades, published in a monthly edition of Shonen Jump. Over the course of his career, he has also used the pen names Asada Hiroyuki and Asada Uchuuichi.

Asada’s early serialized works include the four-volume Bad dane Yoshio-kun, published under the title Bad!! in some regions, followed by the two-volume series Mint: Sleeping Rabbit. He gained wider recognition with the basketball-themed manga I'll, which was serialized in Monthly Shonen Jump from 1995 to 2004 and compiled into fourteen volumes. The series focuses on adolescent characters navigating personal growth and relationships through the lens of sports.

His most internationally renowned work is Tegami Bachi, known in English as Letter Bee. The fantasy-adventure manga began serialization in Monthly Shonen Jump in September 2006. Following the discontinuation of that magazine in 2007, the series moved to Weekly Shonen Jump and later to its successor, Jump Square. The story, set in the perpetual twilight of the land of Amberground, follows a young letter carrier named Lag Seeing who delivers packages while confronting giant armored insects known as Gaichuu. The manga concluded in 2015 after twenty collected volumes.

Asada is credited as the original creator for several anime adaptations of his work. Notably, he is the original creator for the anime special Letter Bee: Light and Blue Night Fantasy, an original video animation released in 2008 that served as a prequel to the main series. The success of the manga led to two television anime series: Tegami Bachi, which aired from 2009 to 2010, and Tegami Bachi Reverse, which aired from 2010 to 2011. Both were produced by Studio Pierrot.

Beyond his serialized manga, Asada has contributed to the industry through other visual design work. He provided the original character designs for the 2016 anime series Cheer Boys!!, a show about a men’s collegiate cheerleading team. He also worked on the 2018 multimedia project Akanesasu Shōjo as a character designer and concept artist. In 2019, he served as the original character designer for the remake of the classic manga Dororo. He has published several art books, including Hone no Saki in 2000, Water in 2011, and the Letter Bee-dedicated Shine in 2011.

Asada’s artistic identity is characterized by a clean, elegant line and a detailed approach to both character design and backgrounds. He has cited his fondness for cats as an influence on the way he draws characters’ eyes. Thematically, his work frequently explores the emotional development of youth, with recurring motifs of dreams, friendship, and familial bonds.

He maintains close professional relationships with several notable contemporaries. He is a friend of manga artist Takeshi Obata, known for Death Note and Hikaru no Go, and the two share a similar artistic style. He also has a connection to artist田岛昭宇, with whom he has been described as having a mentor-student relationship, and together with Obata, they form a creative unit sometimes referred to as Mizugame 3, referencing their shared astrological sign.