The Simplify Brewer is the first piece of equipment Bathtub Coffee made rather than imported. Ryo John Ito founded the Japanese company in 2018 to bring specialty gear into the country, started building his own in 2020 under the line "Be simple, brew perfect", and funded this one on Kickstarter in 2021. It is a straight-walled cylinder, 90 mm across and 85 mm tall, that takes a Kalita Wave 185 paper and weighs about 60 g.
Every feature on it is aimed at getting water out faster. The hole in the bottom is 40 mm, which the maker calls bigger than any traditional brewer; three legs hold the body off the server so air can leave instead of backing up under the paper; and six protrusions on the base push into the bottom of the filter, which Bathtub says keeps water moving inside the brewer rather than sitting still. The paper touches the brewer at very little else — one reviewer counts three points of contact, the top rim, a single support on the wall and the indents around the hole — and Bathtub turns that gap into a second claim: the air trapped between paper and wall works as a "pseudo double wall structure" that holds the temperature up while the brew runs.
What all of that buys is a recipe with nothing in it. Bathtub's own method has no bloom, no circles, no stirring and no swirling: 15 g of finely ground coffee, 230 g of water poured straight down the middle over 30 seconds, then 60 to 90 seconds of drawdown. Ito's argument for the shape is that this is the part beginners get wrong — "circular motion is just difficult" — so the brewer should do the evening out instead of the hand. A finished cup lands inside two minutes.
The material has changed since launch. The Kickstarter units and most of the press from 2021 describe Trogamid CX, a transparent BPA-free nylon, at about 50 g; the current specification reads Tritan™, Eastman's BPA-free copolyester, at about 60 g. Both are plastics chosen for the same reason — Bathtub cites the thermal conductivity of plastic as under a quarter of glass or ceramic, so the brewer steals less heat from the water. It is rated to 100 °C, made in Japan, and sold in transparent or black.
Two things to know before you buy. Flat-bottom papers are the whole compatibility story: it is a Kalita Wave 185 seat and nothing else, which Bathtub frames as a feature, since that is the one flat paper stocked everywhere. And the capacity is honestly one to two cups — the maker's answer to brewing for two people is a video showing two brewers side by side, not a bigger dose.
Starting recipe: 15 g of coffee to 230 g of water (about 1:15.3), water around 95 °C, a fine filter grind, poured in one go into the centre over 30 seconds and left to drain.
