the event being held is a Pokémon united competition.
Food trucks have become big business in Japan and in my view it is one of the final frontiers where small business can get away without paying the proper taxes as most transactions are in cash.
The other advantage of owning a food truck is that you can go where your potential costumers are and set up shop. I have seen many restaurants suffer from lack of parking or degradation of their surroundings whishing they could instantly pick up and relocate. No problem, if you have a food truck.
In Japan, the food trucks I see making the most money are the ones that sell fried chicken and fries, yakisoba ( stir fried noodles), hot dogs, sausages and kebabs. These Items are ready quickly and don't keep the customers waiting. But on this day, you had no choice but to wait as the massive crowd of Pokémon fan’s lined up for some food. 🍲