Mother Reimu's so-called "threatening" actually back-fired: the flapping braids only incited the mice to greater aggression. They leapt forward, one knocking Mother Reimu over while the other tore off one of her braids.
"YUUUUUUUU..." Having seen her most important braid severed, Mother Reimu began to cry; yet for the sake of the little one in her mouth, Mother Reimu had to endure and keep struggling.
Credit to Heptoct for the translation, I only put it in notes.Credit to Zidana123 too, for her more accurate wordings. I can only outline the frame of the passage.