Ao no Hon , The Blue Flame? , internationally known as The Blue Light is a 2003 Japanese film based on the novel of the same name by Yusuke Kishi, directed and cowritten by Yukio Ninagawa, and starring Kazunari Ninomiya and Aya Matsuura. The film portrays Ninomiya playing Shichi, a high school student finding a way to get rid of his stepfather, who returns home and begins to terrorize his family.
Shichi Kushimori Kazunari Ninomiya lives with this mother Yko Kumiko Akiyoshi and younger stepsister Haruka Anne Suzuki. One day, his estranged stepfather Ryji Sone Kansai Yamamoto suddenly returns home and begins to freeload off his family. After Shichi encounters what appeared to be Sone making sexual advances towards Haruka one night, he tries to get rid of Sone. However, Shichi discovers that it is impossible to do so legally.During his art class, he secretly returns home to a sleeping Sone. After thorough research and experimentation on electrocution, he carries out his plan and kills his stepfather. The police declares that Sone had died of natural causes. ........
Source: Wikipedia