Are people really buying so much stuff in Japan to bring back?

I keep seeing on social media and Reddit many tourists bringing back multiple giant suitcases full of stuff they bought in Japan.

Is this very common? What items are these people buying that fills up multiple suitcases? How do they have the time during their trip to buy so much stuff? I have never seen this behavior in any of my other travels except for Japan.

I do always bring back some things from my trips to Japan (like art supplies, snacks, & plushies), but never enough to fill an entire suitcase on its own. Am I missing out on some secret list of items that are must-buys in Japan?

Edit: Wow, love hearing about all the very different, interesting things people are buying in Japan! I really wasn’t sure if people were just bringing back suitcases full of stuff from don quijote lol. You all have given me some great ideas of new things I should shop for during my upcoming trip :)