So, like I have said about Sengoku Rance, this game is a hidden gem, marred by the fact that the gameplay includes lots of adult content. Still, unlike Rance, the MC of Daibanchou is at least vaguely likeable. Unfortunately, it's also an older title, and suffers some definite issues.
Like Rance, trying to unlock everything requires you to basically have the wiki open in the background. Expecting to figure out every potential unlock on your own is absolutely unreasonable, especially given the time constraints in game. That said, one of the big reasons for this is that there is so much content in the game.
Daibanchou is a turn-based, menu-driven strategy game, that takes place in three stages: the short School Chapter, which functions as a prologue and a place to setup your starting party (with 3 binary character choices, where getting one character will lock out another); the District Chapter, where some of the more strategic elements are fleshed out; and then the proper game taking place in the National Chapter. There are also 2 main routes, depending on which of the two main heroines follow you into the National chapter, as well as 4 minor heroines (only one heroine can be cleared per playthrough, but only two determine the overall path of the game's narrative).
The game is great, but as the National Chapter goes on, the micromanagement becomes extremely tedious. As your roster and your need to control territories grows larger and larger. There are many minor phases to each turn in which there are chances for events to occur. First, is the Menu Phase, which is when the game can be saved or loaded. Followed by the Start of Turn Phase, in which generally only one event can occur at a time, and the event which occurs is randomly chosen based on a priority system and what events have their prerequisites triggered, which can be quite frustrating. A couple of minor bookkeeping phases (Income/Prison/Info phases). Then, there is the Main Phase, in which you get a single action each turn (other than a few minor things like managing buildings). Followed by a Conversation Phase, in which Rouga can speak to one of his teammates. Then a Deployment Phase, which leads directly into the Combat Phase, and then the Enemy Turns. The big problem with this is that to clear characters, various actions must be taken, and can only be taken during certain phases. If you have multiple characters that need to be talked to, but no urgent need to invade, you can't forgo invading to talk.
In Sengoku Rance, this was simplified to the Action Fans system, in which many of these 'phases' were condensed into a single Main Phase, in which a certain number of Actions could be taken, but the actions could comprise Events, Invasion, Conversation, Recruitment, in whatever order you please, so long as prerequisites are met and you have enough Actions. This was a major improvement, as it cut down on a lot of micromanagement.
Still, if you have the patience for it, Daibanchou has a much more likeable protagonist and better characters, and a quirky and interesting storyline, and maintains a very similar system to Sengoku Rance. It's one of the few games that scratches the itch left by that game, while I hope that someday more games like it are created.