Masakuni Igarashi is a Japanese manga artist known for creating romantic comedy and comedy series that have been adapted into anime. Born in Kushiro, Hokkaido, Igarashi graduated from Dokkyo University, where he was a member of the university's manga research society. He began his professional career after receiving an honorable mention for the 67th Akatsuka Award in 2007 for his work Taxi Driver. Igarashi made his official debut as a manga artist in 2008 with the short story Dust Shooters!!, published in Weekly Shōnen Jump.

Igarashi's first serialized work was Corpo Paradise, which ran in Kodansha's Weekly Shōnen Magazine in 2014. He followed this with Uneven Animation in 2015, for which he served as the illustrator based on an original story by Miyajima Masanori. Igarashi's breakthrough came with the series Senryū Girl, which was serialized in Weekly Shōnen Magazine from 2016 to 2020 and compiled into 13 tankōbon volumes. The story centers on a girl who communicates only through senryū poetry, a form of short Japanese poem. The manga was adapted into an anime television series that aired in 2019.

In 2016, Igarashi also began publishing Mattaku Saikin no Tantei Tokitara, a comedy series about a past-his-prime detective. The manga is serialized in Kadokawa's Dengeki Maoh magazine, and its 15th volume was released in August 2024. An anime television adaptation of the series was announced for 2025.

Igarashi's most recent major work is Tune In to the Midnight Heart, a romantic comedy about a high school boy searching for a mysterious radio personality he knows only as Apollo. The series began serialization in Kodansha's Weekly Shōnen Magazine in September 2023. An anime television adaptation produced by Studio Gekkou premiered in January 2026, with Masayuki Takahashi directing and scripts written by Yukie Sugiwara. The series is also released simultaneously in English on Kodansha's K Manga digital service.

Igarashi's artistic identity is rooted in少年漫画 (shōnen manga), with a consistent focus on comedy and romantic comedy. His works often feature unconventional communication methods or eccentric premises, from the poetic constraints in Senryū Girl to the washed-up detective in Mattaku Saikin no Tantei Tokitara and the voice-focused mystery of Tune In to the Midnight Heart. His significance in the industry is demonstrated by his ability to sustain multiple long-running serializations across different major publishers, including Kodansha and Kadokawa, as well as the consistent anime adaptations of his popular works.