PSA for chapter 27: Do not soak your newly painted nails in ice water. It only gives the appearance of being harder and will actually take longer to dry. Let the polish dry normally and invest in a quick-dry top coat.
Yankee, not Yakuza.
Though I wouldn't be surprised if there's a similar manga about a scary-looking Yakuza giving helpful everyday tips to people he casually encounters.
@tinysilverstar: Actually it's both right and wrong; what happens is that the surface layer will harden (important if you can't have the tacky nail polish on the surface as you're going about) but the inner layers will dry slower because the solvent can't evaporate as easily. However, if you paint in thin layers, the entire layer will harden up immediately, so for just using a thin coat rather than a thick coat (which AFAIK most Japanese brands are formulated to be thin), this method works just fine. Similarly, if you are doing a topcoat over nail art that you need to harden immediately, without disturbing the nail art (since the solvent can make it streak or bend), doing a quick-hardening process like this can be beneficial there as well. Obviously if you have the time to spare, using a quick-dry topcoat and applying it properly is going to be for the best.
@justforthelulz Gokushufudou aka "The Way Of The Househusband" might be right up your alley, though it's not so much about giving advice as it is about ex-Yakuza being wholesome.