I can't get out of my sister (Volume 1 is the latest issue)

the publisher:
Author: Snowth, Miki
Size: 128mm x 182mm
Number of books: 1
Language: Japanese
Category: Youth manga, manga
Latest release date: 2021-11-29

Synopsis:
I will kill my sister today to protect my beloved sister.
A high school student who has lost his parents in a traffic accident, and his sister, Ichika, has been happy every day, repeating trivial brothers with the cooperation of others.
The usual school road is to walk with the same morning as usual, with Riku's best friend, Ichimatsu.
However, the mediocre days suddenly tell the end.
Because Ichika's hand was killed.
A game of killing each other with the affection of brothers and sisters suddenly starting in ordinary days!