Being a Daimyo is serious buisness. Especially in the Sengoku Jidai, where Japan is a wild land bereft of all trappings of conventional Japanse civlization.
Like Sushi
Or Mangas
Or Karaokeboxes

Thus, my main duty would be to further the development of Sushi, Animes and Karaokeboxes.
In this case, Sushi sounds easiest, as one only need fish, rice, seaweeds and cooks. All of those ingredients should be present in Sengoku Jidai Japan.
I do however have to issue a word of warning, in my first attempt, the fish killed the cook, poisoned the rice and escaped using a rope made of seaweed.
Not to self: Hybrids of poisonous blowfish, ill tempered Orcas and electric eels with futher amplified intelligence I bred for killing Cht'ulu do not make good Sushi.

Concernings Mangas, those need a Printing press. Which is nothing that some sneaky Ninjas on a mission to abduct Gutenberg cannot solve.
Unfortunatley, the first Ninja mission to abduct Gutenberg resulted in getting the ex-defense minister of Germany. While he can faithfully copy written works, his drawing skills are rather atrocious.

From the level of the Sengoku Jidai, getting to Karaoke Boxes no doubt poses the greatest challenge. After all, those need Radio, Television, Computers, and music distribution systems. I intend to fix this with using a variable mod that switches Shogun to Civilisation 4 and back, thus allowing for Tech trades with technological powerhouses. With a focused effort, Getting Karaokeboxes in 200 years should be possible.
However, the fact that my Ninjas kidnapped a defense minister who will not be born in the next 400 years implies that there is a time machine. Should they succeed in either stealing the time machine, or in getting into todays time and stealing a Karaoke machine (as well as the required powerplants), things would obviously become much easier.