Haha! What a refreshing story! This is a surprisingly fun romp dabbling in the supernatural, evil cult apocalypse plot with healthy dabs of Eastern pop culture (and culture, osoreirimasu!), executed deviously with a tongue-in-cheek approach to situational dilemmas. Gold! You're sitting on gold, Mr. Author.
And thank you for throwing in a protagonist who's got a straight head (mostly) on his shoulders, a kind heart (mostly) up his sleeves, and a character progression that actually grows him from a main character to an actual, potential hero. Hats off to you!
First time reader of your novel here. Love the Asian humor undertones, plus some of the few attempts at slapstick comedy. Very few people could pull that off with stills and stylized writing, but you managed it wonderfully. What's amazing is that the slapstick tropes (e.g., bedmate reveals, drop-in characters, comically missing the point, etc.) didn't detract from thematic situational comedy spread throughout the story! Although openings are rare, have you thought of writing for sitcoms?
Psychological horror bits with a taste of Silent Hill, The Suffering, and Outlast sprinkled in for good measure, an oddball, but crass sidekick-slash-wingman (este, a deuteragonist?) you can warm up to, the most colorful crime syndicate conversation this side of Japan, and a shaky, amorous family camaraderie pitted against a common demonic threat... I can't wait for the next adventure you have in store.
Keep up the good work! Thumbs up for you, sir!
Edit: Deuteragonist, not deauteragonist. Sorry.