Basically after watching all the people complain about how the Hattori starting position is horrible I could only think three things:
1. I agree with you absolutely
2.hard, but not impossible
3.It's probably for balancing
Here is a run-through of all the things of all the things you can do. if it says choose a) attack the Asai or
attack the TSui Tsui then for the next step go to 2a) to see how to attack the Asai and so on.
The first thing you want to do is go into the diplomacy panel and make peace with the shogun. If you don't he can be a big problem early on and an even bigger problem if you destroy him. Next you have two choices:
a)go kill the Asai (easier option, less rewarding as well as you may hit a roadblock later on.)
b)Ally with Asai and attack Tsui TSui (Hakatayama will almost surely ally with them in the attack, this option is harder but gives you an edge if you succeed compared to the other option.)
move your army to the border accordingly (if you see a forest beside the border I would recommend using that to keep the enemy from placing their armies into defense mode, I did this and took the Tsui Tsui city fighting only their retainers because they weren't prepared.)
2a. The Asai shouldn't be too powerful. Combine both your armies, leave your daiymo back at your castle and start chopping some purple heads, if you didn't declare war and destroy them this turn your doing it wrong. Don't even try to starve them as their allies might come (they may not be strong but they make up for it in sheer number of allies as opposed to their strength.) Wipe out any Asai rebel armies ONLY IF YOU ARE SURE THEY ARE WITHIN A DISTANCE THAT YOU CAN MARCH TO IN THIS DAY. End turn
2b.Combine armies, leave daiymo at the castle and charge right at their castle (whether or not it has troops.) Speed is of the essence for this plan to work. You should be able to take their castle and produce ashigaru units back at your home province of Iga. Set your new province to repair and spend anything you have left over on your economy. End turn.
3a. From this point onward you should be pretty good you can turn around and go towards the Hakatayama and Tsui Tsui or keep expanding north to the coast and then going either east, west or both along the coastline. Just remember you should be actively producing troops and strengthening your economy as in the early game the upkeep will hit you hard (especially being Hattori.) This is why at this stage in the game you want to keep expanding and conquering while building up an economy so that maybe by turn 10 or 15 you will have lots of territory and an economy that can support your army. At this stage you can keep expanding or decide to settle down for a while and strengthen your economy before moving on.
3b.From here speed is of the essence. Your towns should be producing at full capacity (a building a few larger castle chains would be great for this.) Any captured town should be made so that it can produce the turn after its capture. Do not give the Hakatayama a chance to regroup as their armies are dispersed through their territories but given 10 turns they could easily rig out 5-10 full stacks, on normal. if you manage to take them down build up your economy and conquer the blue guys. From there just keep conquering taking small breaks to build up your economy so that your army can get a larger upkeep. After your conquering of the Hakatamaya you should be the strongest in the game, now all you have to do is keep that up. watch out for the realm divide. make sure your empire stretches coast to coast so that you don't have to fight in 4 directions, just 2. easily defensible locations such as Shikoku and Kyushu are highly recommended. The less front your fight on, the better. You may even want to consider dropping naval warfare if your budget is stretched too tight and focus on land combat for now.
Make sure to always keep an army close to the shogun just in case realm divide starts you should take him out quickly as his army can take over your first provinces which will most likely be your best ones and will seriously reduce your troops production making you very vulnerable to outside attacks. Make sure the army you keep beside him can take out his army and take Kyoto if it should be required.
Why I'm Stopping Here
The answer is simply because there are too many variables by this point. The AI is smart, but unpredictable so any specific advice on what to do from here on in would be useless as the chances you will find yourself in that exact situation by turn lets say 5 or 10 onward is very slim. from here I can just give you tips:
-camp around the shogun to make sure he doesn't destroy your best provinces at realm divide
-get allies and start research the very first turn
-keep good relations with the shogun until realm divide (usually around 17 provinces but be careful 14 and onwards)
-build your economy and stop conquering when you know you are on the brink of realm divide
-do not always deploy via Hattori special deployment, if you deploy a little further away you can start with your units hidden until they get closer or start to attack, and sometimes that's a better advantage then being closer to your enemy
-when using Hattori deployment don't leave your cavalry to fend for itself just because it can't deploy in a special way. leave some troops hidden nearby or tell your cavalry to run and catch up as soon as the battle starts
-Hattori economy is one of its weakest points so make sure to always keep a stable eye on it
-don't just think of the recruitment costs, calculate the upkeep and if you are going to be able to live with that upkeep
-allies are important no matter what way of conquest you pick, make sure to always have some clans (or one very strong clan) you can rely on
-watch you honor, successful ninja missions can give you the breaking treaties -50 on every single on of your negotiations, and trust me it hurts
-you can send your daiymo into battle when you have a sizable force in order to get traits that will increase his honor and the poet trait that gives you faster bushido research
-don't let your conquest fill you with too much of a sense of safety, rebels and armies of factions you defeated may still be wandering your territory so always leave a "policing army" to take care of these problems before they take one of your territories and become a real problem
keep these tips in mind as well as those that you receive from other helpful gamers. Remember this is a clan specific guide so I have missed a lot of general things that are also important to learn (battlefield tactics, managing your economy, ect) so read other guides and ask around the forums to get help on these topics.
Thank you for reading