Yoriichi Type Zero is destroyed at the end of Tanjiro's training, but a sword from over 300 years ago appears from inside. Kotetsu gives Tanjiro the sword, however it is badly rusted. At that moment, Haganezuka appears and takes the sword with him to perform a grueling whetting process handed down within his family line. Meanwhile the presence of demons are inching closer to the village...
It's supposed to take three days
 and three nights to polish a sword...
...قيل لي أنّ صقل سيف يأخذ ثلاثة أيّام بلياليها
Bis das Schwert fertig geschliffen ist,
vergehen drei Tage und drei Nächte, …
Según eso, el pulido de la espada
durará tres días y tres noches.
Le llevará tres días y tres noches
pulir bien la katana.
Et apparemment, il faudra
trois jours complets pour le polir.
वे कहते हैं कि तलवार पॉलिश करने में
तीन दिन और तीन रातें लगती हैं
Per sistemare quella katana 
ci vorranno tre giorni e tre notti.
Dizem que leva três dias e três 
noites para polir uma espada...
Похоже, что на полировку
уйдёт три дня и три ночи.