Let's face it: Rengoku Kyojuro is the king of bento boxes. The Flame Hashira proved this in the premiere episode of Demon Slayer: Kimetsu no Yaiba Season 2. But how many of those beef nabe lunchboxes did Rengoku actually consume when he finally boarded the Mugen Train?
When we first see Rengoku in Demon Slayer: Kimetsu no Yaiba the Movie - Mugen Train, he is happily consuming a beef nabe bento box and declaring "UMAI!" after every bite. Even then, it's clear that the Flame Hashira has gone through a lot of those lunchboxes and the first episode of Demon Slayer Season 2 reveals just how many he had brought on the train with him.
Early on in Episode 1, Rengoku buys all of the bento boxes from the ekiben vendor and her grandmother at the train station. However, he leaves most of it to a Demon Slayer Corps officer and tells him to give it to his companions. Taking a few lunchboxes, Rengoku boards a train headed for a garage pretending to be an ekiben vendor but is told that the Mugen Train is in a maintenance workshop.
Rengoku heads for the workshop, this time telling the workers that the lunchboxes were sent by their boss. It is here that he encounters the demon known as the Ripper, who hates the smell of the beef nabe lunchboxes. Realizing Rengoku is connected to the ekiben vendors, the demon goes after the young girl and her grandmother.
Luckily, Rengoku saves the vendors and is later thanked by the girl and her grandmother as he prepares to board the now-repaired Mugen Train. Although he accepts the ekiben they offer, he then decides to buy all their beef nabe lunchboxes AGAIN. These are the same bento boxes that appeared in the movie.
So what's the exact number of bento boxes that Rengoku consumed? Although he bought about 50 or more in total, he may have only eaten between 20 to 30 lunchboxes. However, this shouldn't be a huge surprise considering that he needed all that energy to take on multiple demons in a span of two days.
Rengoku returns with his bento boxes in Demon Slayer: Kimetsu no Yaiba Season 2 Episode 2, which airs on October 17, 2021.