A supernatural system allows people to take revenge by having other people sent to Hell via the services of a mysterious entity and her assistants who implement this system. Revenge, injustice, hatred, and the nature of human emotions are common themes throughout the series.

After moving into the quiet town of Hinamizawa, Maebara Keiichi spends his days blissfully in school often playing games with his local friends. However, appearances can be deceiving. One fateful day, Keiichi stumbles upon news of a murder that had occurred in Hinamizawa. From this point on, horrific events unfold in front of Keiichi, as he soon learns his close friends may not be all that they seem.

Nagasumi's in hot water after a beautiful, young mermaid named Sun saves him from drowning. The deep-sea sweetheart's dad is a merman yakuza prone to executing anyone who learns his family's scaly secret! Luckily, there's a catch - if Nagasumi agrees to marry Sun, he just might avoid sleeping with the fishes!

Someday's Dreamers is a manga written by Norie Yamada and illustrated by Kumichi Yoshizuki. It was serialized in Kadokawa Shoten's Comic Dragon magazine from May 2002 to January 2003 and was later collected in two bound volumes. In 2006, Tokyopop released the manga in the United States under the name Someday's Dreamers. Someday's Dreamers was also adapted into an anime series that was produced by J.C.Staff under the direction of Masami Shimoda. It is loosely based on the storyline of the first manga series with new characters added to the story. It ran for a total of 12 episodes on TV Asahi and was later licensed by Geneon Entertainment USA. However, due to the closure of Geneon USA, the series has been relicensed by Sentai Filmworks. Another story set in the same universe, Someday's Dreamers: Spellbound, written and drawn by the same author and illustrator, was serialized in Kadokawa Shoten's Comic Dragon Age. It ran from December 2003 to February 2006 and was later released in five bound volumes. In 2006, Tokyopop released the manga in the United States under the name Someday's Dreamers: Spellbound.