A brief description of the manga Kuchi ga Saketemo Kimi ni wa (2019):
Miroku-san meets a little boy who cannot be scared.
Serialization:
Kuchi ga Saketemo Kimi ni wa: (2020 Short) https://www.mangaread.org/manga/kuchi-ga-saketemo-kimi-ni-wa-2020-short/
2.Even if your mouth is torn: https://www.mangaread.org/manga/even-if-your-mouth-is-torn/