Akamatsu has been a managing director of the Japan Cartoonists Association since 2018, and is a vocal advocate for protecting freedom of expression in manga and anime from expansions in censorship and copyright law.

[3] His father, a bureaucrat in the Ministry of Agriculture, Forestry and Fisheries, was often transferred, and the family lived in Yamagata, the Kita ward of Tokyo, Kumamoto, Higashikurume, and Kawasaki.

[2] Akamatsu attended private Kaijō High School in Shinjuku, Tokyo, and entered Chuo University's Department of Japanese Literature.

became the first to carry a "Doujin Mark" indicating explicit author permission for use as a source for fan-made works, the result of a publishing initiative led by Akamatsu.

The site gained notoriety later that year when it posted Seiji Matsuyama's Oku-sama wa Shōgakusei [ja] ("My Wife Is an Elementary Student") manga, which Tokyo Vice Governor Naoki Inose had cited as an example of a work that should be restricted for physical sale under Tokyo's recently revised Healthy Development of Youths Ordinance.

Akamatsu is a vocal advocate for protection of freedom of expression in anime and manga, and has been an opponent of government attempts to expand censorship and copyright law.

Akamatsu visited the National Diet and the LDP headquarters to express his concern, and the final bill passed in 2014 without a ban on explicit anime and manga.

[10] In 2020, Akamatsu was invited to advise legislators in the Diet on the future of manga, stating that "[c]ompared to other countries, Japan's forte is its freedom of creativity" and that "a situation where Japanese works are regulated by foreign standards" should be avoided.

[10] An early initiative of his was a task force on a proposed legal framework for preservation of past and present Japanese video games in a playable state.