You can check the artist's history and related "Umi Chan" entries on The Doujinshi & Manga Lexicon to see high-resolution cover art and publication dates.
Shichi Umi Chan is known for a specific aesthetic. Comment on the use of lighting and how the "tan" skin is rendered, as this is a technical highlight of their work. You can check the artist's history and related
: Expect themes involving "tan lines," classroom settings, and the specific aesthetic associated with "kasshoku" (dark skin) characters. Where to Find It " classroom settings