Tanjiro's wounds have healed, so he first visits the former Hashira, Uzui, to join the Hashira Training. Tanjiro's joy for the reunion with Uzui is short-lived, however, as he will now undergo basic training to boost his physical stamina.
what could be behind that door.
.كان يشغل بالي منذ ذلك اليوم
Was ist da hinter dieser Tür?
¿Qué había detrás de esa puerta?
¿Qué hay al otro lado de la puerta?
Qu’est-ce qu’était cette porte ?
Cosa c'è dietro quella porta?
No que poderia estar do 
outro lado daquela porta.
Что же скрывалось за теми дверьми?
ที่เห็นหลังประตูบานนั้นคืออะไร?