After completing training with Uzui, Tanjiro visits the Tokito residence next. The Demon Slayer swordsmen who have already started the training are dispirited by Muichiro's intense training and harsh words. Tanjiro hears the swordsmen discussing if there's anything they can do about it...
he says he had such nerves of steel
that he could sleep through a thunderstorm...
وهو يملك أعصابًا من حديد حسب قوله لدرجة
...أنّ بمكانه النّوم حتّى أثناء عاصفة رعديّة
estaba tan insensibilizado que podía
dormir aunque nevara o tronara.
il a toujours eu des nerfs d’acier,
au point de dormir
ha sempre avuto dei nervi così saldi
ele diz que tem nervos de aço,
a ponto de conseguir dormir numa tempestade