On the surface, Vongola looks like a company and is a big family in Italy. However, in fact, they are actually a detective agency that takes over commissions from various countries every day. This time, the Italian government gave them a commission to eliminate the international criminal organization "Wine". Therefore, Sawada Tsunayoshi, the tenth leader of Vongola, and his guardians came to Tokyo...
After Tsunayoshi and the others solved "Wine", they received a commission from the Japanese government and a letter from the ninth generation. So, Tsunayoshi and the others came to the detective school called "DDS"...
[I suddenly thought of it, so I added it in. The early period was Conan, and the later period was a series/manga called "Detective Academy Q". Because it is an old series (after all, he is the author of Kindaichi), so few people probably know it, but I recommend you to read it. There are a lot of brain-burning reasonings in the manga (for me). By the way, I stream Q on my site~]