Instead of giving Kiryu cancer and putting him in Y8, they should have just made Kiryu a full time secret agent indefinitely with a bunch of his own little spin-off games. So like

>Like a Dragon Gaiden 1: The Man Who Erased His Name
>Like a Dragon Gaiden 2: Pirate Yakuza in Hawaii
>Like a Dragon Gaiden 3: Something Something Akiyama Falls Asleep On the Couch Again
>Like a Dragon Gaiden 4: Return of the Hidden Dragon
>Like a Dragon Gaiden 5: Saejima Ate Some Bad Meat and Got Food Poisoning