His career suddenly took a turn when his other brother who was supposed to succeed Naoaki Ii, 12th generation, passed away. And when Naoaki passed, Naosuke inherited Ii Clan's 350,000 Koku (see Notes l) as 13th Hikone lord. Naosuke was reported to have distributed 50,000 Ryos (see Notes 2) among his clan samurais, merchants and farmers according to the bequeathed will of Naoaki, his foster father. The generous 50,000 Ryos were comparable to a year’s income in the Ii Clan. He also financially assisted temples and the like, reinvigorated Kodokan, school for children, banned the red light district, and the people hailed him as benevolent lord.
As mentioned earlier, Naosuke studied Japanese Classics and revered the emperor but remained as Tokugawa's caretaker. It is a tragic tale of a bogwood-to-be-samurai who grabbed prestige and power second only to the Shogun. After Naosuke’s death the Ii family was disgraced for many years. Recently, however, Ii’s actions have been looked at in a more favorable light and Ii Naosuke has taken his place as one of the most important political figures in Japanese history.
1) "Koku" was a unit of fief wealth. Originally one Koku was the volume of rice a person can eat in one year
2) "Ryo" was an Edo period currency, available as Oban (large size coin of higher denominations) and Koban (small size coin of lower denominations).
3) Hikone Museum exhibits artworks of both Sekigahara Battle and Sakurada Gate Incident