All Memoirs of a Dragon in Like a Dragon: Infinite Wealth
The full list of Memoirs of a Dragon in Like a Dragon: Infinite Wealth
The substories in Kiryu’s part of Like a Dragon: Infinite Wealth are slightly different from Kasuga’s. Most of them appear as gold circles on the ground throughout Ijincho and Kamurocho, but some require other things to unlock first. This can be story progression, some side missions, and completing some Life Links with Date.
If you have missed some of these, it could be that you are not there at the right time of day. Some are night and day dependent, so you should check your map frequently in case a new one pops up.
Here is the full list of Memoirs of a Dragon in Like a Dragon: Infinite Wealth: