From the Facebook page Please Stop the Sale of Tatsuya Ichihashi's Book comes this:
I have no idea if the above is true. If a movie does get made, There's no point in being outraged until one sees the final product. Movies about bad people are created all the time, so a film about Ichihashi is nothing to be upset about. With the update below, consider me underwhelmed that the producer intends to not portray Ichihashi in a good light. Was there something glamorous about the murder and life on the run that I missed?
UPDATE: More from The Japan Times:
A movie based on the book written by Tatsuya Ichihashi, whose slaying of a British English teacher in 2007 set off a nationwide manhunt, will debut next year, the publisher and film producer said Thursday.
Producer Sedic International told publisher Gentosha that it wanted to turn its book — "Taiho Sarerumade — Kuuhaku no Ninen Nanakagetsu no Kiroku" ("Before I Was Arrested — Records of the Blank Two Years and Seven Months") — into a movie and got the OK, a Gentosha official said.
"The incident grabbed a lot of social attention," Sedic International's Kensuke Zushi said. "We have no intention of casting Ichihashi in a positive light."
The movie will mark the directorial debut of Japanese actor Dean Fujioka, who will also play Ichihashi in the film. Casting has not been completed for the other roles, and filming will begin in January, Zushi said.