If you have managed to get the Otherworldly Thirst achievement either by walkthrough or your own discovery then congratulation on unlocking Yashiro aka mr Faith. Now with those who have heard of the incredible trilogy before you would also notice another achievement referencing it concerning mr priest here called Rain of spider requiring you to beat the game against the spider god on True Believer using Yashiro. Now at first glance this seems ridiculously difficult because Yashiro's kit is built for escaping combat and being rewarded for it which is disabled when you have the spider god. I'd like to share what i think is the easiest surefire way to get this achievement, via power of friendship.

Now a lot of the powerful builds in this game is based on the characters and their features like Ayaka with her curse stacking so not a lot of stuff can be used between characters. However, becoming a stand master with an army of allies to beat up the enemies does. First of all, start a run with either timeline, i used A for my run, and select the hunted by cultist background. This is important because during this run the only real threats are skill checks and doom meter. Now onto the mysteries, reroll until you get the eels and the festival, those are only essential ones. Additionally, you could also try to include Manto in there for his doom reduction mask but it's not strictly necessary. As for the locations, have the illegal den and monument for seaside and that's about all you need to start.

What you want to do is start off with the eels and keep Kana alive. When the loan guy comes asking for your payment just choose to use the jar of blood. Don't pick doom or reason because events can really mess you over especially with a lot of the spider ones draining reason. Before you investigate anything, head straight for the den and recruit 3 allies doesn't matter who, this is likely the only time you would use a shop area during the run unless you need to head to the pharmacy for meds in emergency. Then, just progress the mystery like normal, ignoring the side objective and choose to poke her eye out at the end.

With Kana by your side early on you can avoid a lot of the damage with her ability which is crucial against some of the meatier enemies that you can't kill reliably. Let's talk about the festival, spam the ♥♥♥♥ out of the recruit option. Every time that the festival isn't open just choose to rest a bit in the inn to recover your reason, stamina isn't a main concern. You should get around 4 allies or 3 if you're unlucky though that doesn't matter much since you're already amassing quite a crowd. Proceed like normal and end the mystery.

Congratulations, your ally attack now does around 14-16 damage per hit, enough to 2 shot almost all enemies and 1 shot the squishy ones like young witch. Just go in combat, prep attack, ally attack then rinse and repeat. Since the enemy are only hitting you once at best, Faith actually stays consistent and even increases the more you progress through everything. There are additional events to acquire more allies like the hooded people in village, dock event in seaside, dog in forest or crazy patient but only look for these if you're comfortable with your remaining doom. If not, then at around 70% doom, you should have a weapon by now dropped from an enemy if not the gun cultist who is almost guaranteed to have encountered at this point. Equip the weapon then bully 3 random student in your street gang of a team. But seriously, 14-16 damage a turn is more than enough, don't worry about combat too much.

Important note: DO NOT pick Zeal while levelling up, +1 damage isn't worth having max stamina and reason decrease. Since this build if you can even call it that doesn't rely on any stats, you could have sub 5 charisma and still clap the enemies so stats are sorely for skill checks and you can instead just dump them into either stamina or reason, whichever you're low on. Only rest if the maximum gain can be achieved as in +2 stamina AND reason. Note down the second enemy and mystery, if you have played the game until this point and doesn't do that then you deserve to lose the run to doom.

And that's it, have fun steamrolling through this "challenging" achievement using friendship. Normally, this tactic often used with Mizuki runs into the issue of ghosts but Yashiro's crucifix allow your homies to gang up on them easily. Faith isn't something to worry about, even as i dodged no attack i still ended my run around 18 Faith. With that, i bid you luck with the challenge runs for the full completionist experience, have a good one.