Hakoisse (箱いっせ)

A white, round SOMETHING has appeared in the Sea of Japan! The notoriously lazy Harusame gets appointed as the mysterious marine creature "Shiromaru" handler along with two quirky companions! While Harusame wants nothing more than to avoid human interaction, his encounters with Shiromaru force him to confront the past... A coming-of-age sci-fi drama for anyone who finds this world hard to live in! (Source: MangaPlus)

Meet Linear Seven, an alien observer of other alien life forms. When news breaks that Earth is doomed to extinction, she makes her decision: "It's now or never!" And so begins her journey to Earth... Part of the 10th anniversary Jump+ One-shot collection

After being made to read a bizarre manga about three demons seeking "The Witch's Hexhand," Sora, a 30-year-old municipal office worker, gets caught up in the schemes of three children... Featuring horror! Youth! And a dash of romance! A mysterious horror fantasy revolving around "The Witch's Hexhand"!