Played enough of the game multiple times to get the hang of things. All endings and H-content unlocked.
General character information:
Characters are asked in a cut-scene about their future roles when players reach level 5 in the dungeon. As soon as they make it to level 7, the girls are promoted based on whether or not the instructor has had his way with them through blackmail sex. Players who rush through the game without blackmailing anyone may have to wait until level 9 before the promotion is given. The tipping point appears to be the first scene involving penetrative sex. To be safe, players who make it to the second variant should get the "alternate" upgrade path.
Characters:
Ouka - Melee fighter. Upgrades to Paladin or Samurai (Alternate)
Has no skills except a regular attack until she upgrades. As a Paladin she gets a basic heal and mass heal, but her abysmal magic stat means she doesn't do much aside from remove status debuffs from her teammates. The Paladin passive lets her take a hit aimed at a teammate 20% of the time and she'll do it even if she's asleep or confused. The Samurai passive gives her a double-attack 20% of the time, however the second hit is subject to the same miss chance like all regular attacks. Despite the high HP pool relative to the other two, her poor magic stat means the late-game magic attacks will bring her to death's door more often than her teammates.
Equipment: Swordsman can use most melee weapons bar the Japanese (Kotetsu, Katana etc) ones. Paladin is much the same as the Swordsman while the Samurai can only wield Japanese weapons and daggers.
Lee - Healer. Upgrades to Bishop or Monk (Alternate)
Vital to the party despite her average melee damage, she learns more healing skills which become more potent as she levels up. Of the three her defensive stats are the most balanced, but her HP pool isn't high so sustained attack will incapacitate her so buy some resurrection potions to keep her going. The Bishop gets no passives and has extremely restricted equipment choices (Staves only), so any gauntlet she's using as a priest is unequipped and unusable for the rest of the run. The Monk passive lets her ignore enemy defence 20% of the time, but she needs a decent weapon (Monks have more or less the same loadout as priests) to really take advantage. Because her H-scenes have a lower threshold than the other two, it's highly advisable new players go for her ending first to get the monk passive since the two late-game healing abilities are also obtainable as a monk.
Equipment: Gauntlets and Staves. Bishops can only use Staves. Monks can use the priest loadout and a couple more options.
Keela - Mage. Upgrades to Sage or Summoner (Alternate)
Negligible physical damage, so use those spells she has and keep casting them to increase the maximum number of uses. As she levels up, she gets more elemental spells for offence. Abysmal HP and defence stats so players have to baby her early in the game when physical attacks are more prevalent. Ironically she does all right towards the end as almost every attack then is magical which she is better at defending. The Sage gives her an astrology passive which lets her evade any attack 5% of the time, she also gets the upgraded heal and mass heal spells but doesn't have the maximum number of uses Lee has. The Summoner initially gives a weird defence boosting spell which lasts for one turn, later she gets a powerful AOE lightning spell which needs two turns to activate. Summoner has the superior weapon selection, so definitely better in the melee front than the sage.
Equipment: Daggers and Staves. Summoner can use proper melee weapons like Spears and bows, so her physical attacks when she's out of spellcasting are better than token damage.
Scene guide
Bugging the various areas prior to dungeon exploration is what gives the instructor the leverage he needs to earn sex scenes. When he's got enough dirt, he'll give a short dialogue featuring a girl when she's "eligible" for the next sex scene. Once players have unlocked the necessary scenes, no need to bug that particular location further.
Changing room scenes: Clothed and naked ones require bugging the changing room. Lee needs the tier 1 camera for the clothed scene, the other two need the tier 2 camera. For Lee's naked changing scene, tier 2 camera is enough. The other two need tier 3.
Shower scenes: Lee's first scene needs tier 2 camera. If the failure dialogue pops up after Lee's first shower scene, switch to tier 3 to obtain the rest of the scenes.
Toilet scenes: Lee's first and second scenes need tier 2 and tier 3 cameras respectively. For the other two, their first toilet scene needs a tier 3 camera. The second toilet scene variant requires the player progress far enough with the blackmail sex AND make it far enough down the dungeon before it unlocks.
Ouka bedroom: View the lingerie changing scene and the two rule violation scenes here. Tier 2 for the changing scene and first rule-breaking scene, tier 3 for the second rule-breaking scene. If the 2nd rule-breaking scene doesn't trigger, go deeper into the dungeons and try again.
Lee bedroom: Changing scene is tier 1 camera. School violation 1 needs tier 1 and tier 3 for the other scene.
Keela bedroom: Changing scene is tier 2. Rule-breaking 1 tier 2, rule-breaking 2 tier 3.
Endings:
1. Ouka pregnant end
2. Lee pregnant end
3. Keel pregnant end
4. Harem end. Should be enough to get all the girls on H-scene #5 at least once, but I couldn't get the behemoth to spawn so spent a few days seeing all of their final H-scenes before looking for the Behemoth.
5. Normal end. Defeat the behemoth at level 9 without blackmailing any of the girls.
6. Defeat the boss monster at floor 50. If there's going to be extra content for this game, it's most likely an extension of this plot point. Trouble with levels 10 and 11 is the complete absence of healing fountains. The twisting labyrinth layout also wastes a lot of time and action points on exploration.