Rust-Eater Bisco 4 Gyou Hana no Teikan Muri, Hanataba no Ken

is the fourth volume of the Rust-Eater Bisco light novel series, written by Shinji Cobkubo and Illustrated by Akagishi K. It was released under the Dengeki Bunko Imprint in July 2019.

Synopsis
Kantsubaki saves the King's son, who is surrounded by the rich scent of death. It was the one who saved Shishi, a child who escaped from the boiling sea of fresh blood. "If you know who I am." Gale unreliable older brother-it was Akaboshi Bisco. Kyushu's huge prison "Rokudo Prison". There was a clan of Benibishi, an android who manipulates flowers, imprisoned there. Red rhombuses are oppressed in prison, carrying a fate that cannot be resisted by humans. However, it is also the red rhombus that manipulates the cherry blossoms that captures them. Flowers that take away the vitality of mushrooms and are in full bloom. The unknown flower power generated by the spores of the evolutionary mushroom "Nanairo" moves Japan!

(source: Dengeki Bunko Official Website - Translated)

Characters

 * Bisco Akaboshi
 * Milo Nekoyanagi
 * Paw Nekoyanagi
 * Chiroru Oochagama