FourSix is named after a method of brewing coffee called the “4:6 Method” invented by Tetsu Kasuya, former World Brewer’s Champion.

Tetsu Kasuya demonstrating his 4:6 method of brewing coffee

“A new coffee brewing theory created with the concept of ‘easily-brewed delicious coffee for everyone.’ Divide water into a ratio of 4 to 6. Adjust taste with the first 40% of water and density with the remaining 60%.

“The point is to use coarse grounds and make the second pour after the water from the first pour completely drips through.”

Description from the Hario Japan website
FourSix has no affiliation with the HARIO CO, Ltd. or Tetsu Kasuya