Rekomaru Otoi, also written as Rekomaru Otoi, is a Japanese manga artist born in 1984. He is best known as the creator of the manga series Ojisan to Marshmallow, which was adapted into a television anime in 2016.

Otoi began serializing Ojisan to Marshmallow online via the Pixiv community, where it garnered over 20 million views. The manga was later acquired by Ichijinsha, with the first tankobon volume published in 2014. The story, a romantic comedy centered on the relationship between a marshmallow-loving office worker named Wakabayashi and her older colleague, Habashira, ran for five volumes until 2017. The 12-episode anime adaptation, produced by the studio Creators in Pack, aired in Japan between January and March 2016.

Beyond his most famous work, Otoi has created several other manga series. These include Wakabayashi-kun ga Nekasete Kurenai, a spin-off of Ojisan to Marshmallow, which was serialized in Futabasha's Manga Action magazine from 2015 to 2018. His other works include Sono Toki no Kanojo ga Ima no Tsuma Desu, an omnibus romance manga published in Kadokawa's Monthly Comic Beam from 2019 to 2020, and Usobitchi Senpai, which began serialization in Houbunsha's Weekly Manga Times in 2019. He is also the author of Sekai wo Sukuu Tame ni Ajin to Asa Chun Dekimasu ka?, which has been serialized in KADOKAWA's Young Dragon Age since 2017. In addition to his serialized works, Otoi has contributed illustrations to other projects, such as providing an ending illustration for the television anime Tsugumomo. He has also been known to use the alias Toire Komeru.