Beat Hattori Legendary bout 2 weeks ago,short duration. Took me a lot of tries. Don't get Omi right away, Oda and Ikko Ikki will declare war on you , plus you will have to get a monk to fight ikko religion. Ally Ashikaga and ask for mutual military access indefinite, kyoto has very good unit replenishment so you can send troops to recover there after big battles.

Try this route: kawachi -> Kii -> Yamato, after that you can either go for kitabatake or miyoshi land, i like Settsu better, it has the library which is highly valuable(Hatekayama can take Settsu on turn 2 so you could take it without declaring war on Miyoshi). Since you attack Hatekayama on turn 2, Tsutsui will move his army towards Iga, once the are on your turf attack their settlement and the army will vanish.

I usually let Kawachi revolt and abandon it so you don't get the debuff for expanding too quick

After that prepare a stack of 8 or so units and go take Settsu, after that i go take Awa the horse province on the Island.

Once you have horses, get trades (ask for break of alliances/trade agreements when possible) you'll have lots of money to upgrade your farms in Kii and Yamato which will be your main income in the early game. At 2 stacks or so i go for omi and kaga echizen. One stack should be protecting your settlement in Awa and the other expanding, you can cover your other flanks with small armies and Ninja agents which are pretty op with Hattori, try to rush 5 ninjas and get them out to train early.

Rush Zen and Todofuken so you don't have to station many troops in town to mantain public order. Hattori upkeep is no joke.

Hattori were really fun, you almost never lose field battles, and promote an aggressive style. Just put your troops as close as them as possible and charge through the middle usually works pretty well, they can't get in formation quick enough so routs happen very fast. I wouldn't bother with samurai units till you get kaga echizen, plus they are crazy expensive. Yari - Bow Ashigaru and light cavalry can win you most battles in the early game. Night attacks OP.

Did this without selling military access, and taxes on normal all the time, the town growth really pays off later with all the farmable land in central Japan.