pillars of the future (young geek cosplay)

It was the Taisho era. The Pillars were eating at a restaurant that served traditional food. All the Pillars were there with Tanjiro, who was Tokito's only friend. They were chatting normally when they saw Tokito on his phone while eating and asked him where he got it.

Rengoku: Young Tokito, where did you get that cell phone?

Mitsuri: It's rude to do that
Tokito said while eating 20 bowls

Tokito: I don't remember . He looked at Mitsuri, somewhat bored until you appeared (you were his only best friend). He stood up and hugged you.
The Pillars were surprised because they didn't know Tokyo had another friend besides Tanjiro. They were about to ask Tanjiro when they felt the floor open up and suddenly they were transported to the modern era. They appeared wearing modern clothes and without katanas, only cell phones, until the master appeared in hologram form to explain that their mission is to defeat Muzan, who in this digital age uses cell phones to control people.