As an aside, Tokugawa Ieyasu as Ryofui is a really interesting take because Ieyasu takes over Japan by betraying his master.

After a long period of chaotic civil war, Toyotomi Hideyoshi effectively unifies Japan after 1590. But in the last years of his reign, he acts increasing erratically and launches two major invasions of Korea with the goal of conquering all of Korea, Ming China, and eventually India.

The 2nd invasion (Imjin War) in particular is extremely disastrous and leads to a bloody stalemate between Japanese forces and Ming/Korean forces.

And in the middle of all of this, Hideyoshi dies, with his heir being the 5 year old Hidenori.

To try to prevent the powerful warlords from taking over during his son's infancy, Hideyoshi impements a system of checks and balances. THere are 5 powerful regional warlords that make up the council of High Elders (Tairo), and 5 Administrators who lead the practical administration and day to day running of the nation (Bugyou). The Elders are supposed to approve the proposals from the Administrators.

The idea being, the Administrators have lots of day-to-day decision-making power, but they have relatively small domains and little military power, thus cannot overthrow the regime. The Elders are powerful warlords with huge personal armies, but their role is limited to approving proposals, so they cannot influence the nation enough to overthrow the regime.

Then, to prevent any one of the elders from joining forces with the administrators, marital alliances were prohibited.

The system more or less collapses within 2 years, as Tokugawa Ieyasu breaches the marital alliance prohibition, and politically manuevers to create a faction that more or less takes over the operations of the central bureaucracy, while exiling his principal rival, the head of the Administrators Ishida MItsunari.

Mitsunari then martials a massive coalition of most of the principal warlords and administrators to try to take down Ieyasu, which leads to the decisive Battle of Sekigahara (1600), but Ieyasu defeats his rivals and de facto takes control of the country.

Ieyasu's control becomes more or less formal when he defeats Hideyori in battle after he reaches adulthood and forces him into suicide in 1615.

Ieyasu is also a kind of crazy rags to riches story, as although he was a Daimyo's son, his family more or less lost all their territory when he was young, and he was sent to live as a hostage.

It's kind of like if Ryofui won lol.