Episode 9:
It's totally possible, that the blue-one's (I do not care enough to remember all their names, come on) mother killed herself to protect him. Because if she did not, it would be potentially possible to determine, that he killed the father, but since she killed herself, whatever investigation was started (if any) would consider her killing the samurai and then killing herself, which would leave the boy outside of any possible suspicions. If any, considering that it did not look like anyone was searching for him either way.
