Finally, from January to August, I completed a marathon of the Yakuza game series (including only the main timeline games, without spin-offs). Therefore, a brief summary of all the parts (similar to Kingdom Hearts):
Yakuza 0: The two main characters supposedly don't know each other, but they know each other mentally
Yakuza 1 (Kiwami): A fight over 10 billion
Yakuza 2 (Kiwami 2): a fight over the clan's heir (with the best villain in the series)
Yakuza 3: the most boring game in terms of plot and gameplay, so I don't remember what happened there 😅
Yakuza 4: a story with four protagonists (just like in JoJo)
Yakuza 5: I had to skip it because there was no Russian translation, sorry
Yakuza 6: it's pretty much the same, so I'm sorry again
Yakuza 7 (like a dragon): If they mixed an improved version of Boruto and Persona 5
Yakuza 7.5 (Gaiden): Some off-screen plot that no one cares about
Yakuza 8 (infinite wealth): Same as 7, but with a new location in Hawaii
Yakuza 8.5 (Pirate Yakuza): One Piece if Oda had actually stopped at the 5th volume of the manga instead of continuing for 25 years! So: https://youtu.be/gWo12TtN9Kk?si=tyRIJRgDnTDPzdjO