Just adding a little bit of information since the battles aren't actually that easy unless you're heavy overleveled.
ALSO TAKE NOTE: YOU DON'T NEED NG+ OR HARDER DIFFICULTIES, YOU CAN H ALL BOSSES IN YOUR FIRST PLAYTHROUGH
Here are a few recommendations to add upon Ryu's guide:
Chapter 1:
-Attend the meetings
-Once you gain some levels distribute your points on attack, defense and buff skills
take note on "chain stasis" for Kirara it'll be useful for later.
-This is the only chapter where you cannot train freely, so make sure to attend some speeches for quick level up
-Attend all events concerning Maino (The quickest you can get her skill is day 7, day 9 the latest) *don't forget to equip the skill*
Boss battle recommendations: At this point you don't have many abilities to choose from so stick to a pattern
that's the most comfortable for you. Go with Akashima calibur + medical alone + opressive silence, pretty straightforward.
Buff any attack with Endeavor Mind and pummel Maino with it, you'll know you succeeded in hitting her with it if you see the legends = "The system is right" "effort is supreme"
Always save green audience to be able to heal after Maino's attacks. don't worry if she heals herself, you'll eventually bring her down.
-Recommended level: 6 (you can level up in the training tutorial)
Chapter 2:
-This is a tricky chapter (assuming you want to get the skill and H the boss)
-Attend the meetings
-Attend ALL of Rei/Tomori events
-Even if you're pressed on time TRY to attend Yumina events (at least 2 out of possible 3) *this doesn't include free day events*
-DO NOT attend speeches ,you simple don't have time to spare.
-DO NOT train before getting the skill, again you don't have time.
-DO NOT attend Ai or Kirara's events unless there's nowhere else to go.
-You will get the skill on afternoon of the 9th the quickest, and morning of the 10th the latest *don't forget to equip the skill*
it's possible to get the skill on the afternoon of the 10th but by then you won't have time to train,
you'll have plenty of trouble bringing down the boss if that happens, so make sure to have at least
a single half a day to train.
-Boss battle recommendations: have Ayumu on wait till you have enough red audience then hit Rei
with sister blade as soon as you can. This will make Rei retreat and save you from getting hit with
his devastating special move. Take care of his cohorts with your poisons of choice, use debuffs
carefully as they lower approval, heal only when necessary, Hydroblast should be saved for that annoying healer.
Sister blade is expensive so make sure to buff desperado, disruptor and yumina charge with
rising one/Endeavor mind as often as you can. Once the henchmen are done Rei is easy.
if you can, sister blade him once more to make quick work of him.
Recommended level: 9
Chapter 3:
-Time pressed on this one as well..
-Train as soon as you can (before the miko sisters events appear)
-Use your points to level up your defense and counter skills
(if you don't have chain stasis or null silencer, train them then buy them at the store.
Do the same for Fire helm/utter indifference/hyper guard and smile/cloak of suffering)
Also train attack skills and buy them as well since your old attack skills won't be enough
for the next boss battle. If you can, get: Akashima avalance, devastator, Yumina dynamite,
Healing all, Manifold bite)
-Level up and equip Yumina song skills, they will be extremely useful for the remaining boss battles
-Attend all meetings
-Attend Yumina events as usual (at least 2) *again, this doesn't include free day events*
-DO NOT attend speeches
-DO NOT train more than once unless you've secured the skill
-Attend Tsukuyo's events in the afternoon (several of her events are only available in the afternoon)
Youko events can be attended anytime but best to leave them for the mornings.
-You'll get the skill on day 9 the quickest, day 10 the latest (if you didn't train earlier make sure to save an afternoon so you can train before the battle) *don't forget to equip the skill*
Boss battle recommendations: The sisters can deal tons of damage, you need to get Tsukuyo to retreat and defeat Youko first since she's the most
dangerous. First have Ayumu on wait to build up red audience then hit Tsukuyo with Independent heart, once she retreats pummel the henchmen with
your strongest attacks,(have chain stasis and null silencer handy for those chain attacks)
once you clear some room, go all out on Youko, don't hesitate to use debuffs.
you'll notice your approval is extremely low. Don't panic, you started with 10% or so... the problem is that even if you win the battle, if your approval is not at least
51% you'll automatically lose. If you have followed the strategy thus far Tsukuyo should be the only one left, now's time to switch Yumina to the front
row and have her sing "You don't have to be Cinderella" this will rise your approval substantially and Yumina will be moved to the back row where you
have to keep spamming her song until your approval is high enough, once you get to 70% or so, independent heart Tsukuyo's ass into oblivion.
Recommended level: 12
Chapter 4:
Easier than previous chapters since you have some time before Nayuta shows up.
-Train your ass off, but just once. This means enter Ordacle and GRIND GRIND GRIND in the span of half a day.
-Attend all meetings
-Attend Yumina events (at least 2) *there's no free day on this chapter, as classes have been suspended*
-Attend all of Nayuta events
-On the final Nayuta event pick the choice= "I can't make any promises" After this attend the final clubroom meeting to acquire her skill.
(You'll get this skill on day 9, might be possible to get it on day 10, though i'm not sure) *don't forget to equip the skill*
-Train all the skills you can and buy them from the store, especially attack skills since you'll need them to actually manage to deal decent damage
to Nayuta, recommended: Akashima divider/Yuminaza 100t/Irradiator/Lacerate Flesh
Boss battle recommendations:
Nayuta fights you solo. Seems simple enough but her defensive values are broken. You need to be fast on lowering her HP to 15% or she'll catch
you on a total defense loop till you break. Also you start with very low approval...
First things first, Have Ayumu chill out for a turn, then after Nayuta attacks red audience will skyrocket, quickly move Ayumu to the front and pummel
Nayuta with Absolute Horizon- Don't hit her again with it till she's nearly dead (horizon is crazy expensive and it only has 2 uses) switch Ai to the front and
have her cast Irradiator buffed with whatever you can. If you have "sincere brainwashing" (it raises approval) use it to counter Nayuta's heavy defense buffs somewhat,
then proceed to slap her with your mightiest attacks (Akashima divider works fantastic against her) don't use Hydroblast since it will kill your approval very fast, and
only heal if absolutely necessary. Once she's close to defeat, spam every turn "You don't have to be Cinderella" once again to rise your approval, but take a note:
You need 90%+ approval to clear this battle (any less and you'll automatically lose, so be careful) Once you have over 90% approval, impale Nayuta's asshole
with the last Absolute horizon(or whatever skill you have left) to finish her off.
Recommended level: 16
That's it, hope it helps you :3