Rei Kiriyama is an extraordinary shogi player. Among the few elites to have gone professional as a middle school student, he is considered a genius. But what lies behind his prodigious facade is a teenage boy who suffers immense pressure from both his family and from the high expectations from the shogi community. Rei moves out to live a more independent life away from his family, but his unorganized lifestyle and unsociable personality show no signs of improvement.

However, in a twist of fate that will prove to be a turning point in his life, Rei encounters the Kawamoto sisters—the motherly Akari, the passionate Hinata, and the energetic Momo—who take great care of him. 3-gatsu no Lion tells the story of Rei as he reshapes his melancholic life and picks up the courage to begin facing the problems he evaded during his past.

3-gatsu no Lion was nominated for the second Manga Taisho Award in 2009 and won the fourth Manga Taisho Award in 2011. In the same year, it also won the 35th Kodansha Manga Award in the General category, along with Uchuu Kyoudai. In 2014, the series won the 18th Tezuka Osamu Cultural Prize Grand Award. The manga won the Grand Prize in the Manga Division at the 24th Japan Media Arts Festival in 2021.

The series has been published in English as March Comes in Like a Lion by Denpa since June 6, 2023. It has also been published in Italian by Panini Comics since February 13, 2011; in Spanish by ECC Ediciones since October 31, 2017; and in Polish by Dango since April 26, 2019.

The manga was adapted into a two-part Japanese live-action film that was released on March 18, 2017, and April 22, 2017, respectively.