Kirin claims the secrets to the luxurious taste of its Koku no Jikan or full body taste time 3rd category beer are 1) an extra amount of barley and 2) a extra aromatic hops. Keep in mind that maintaining a non-beer status requires balancing the amount of barley (keeping it low) and the amount of non-beer alcohol added. A company can call their "beer" 100% barley derived if the shochu spirit or alcohol that is added is also derived from barley. This is a careful dance to avoid taxes that is very out in the open and which most Japanese beer drinkers are aware of to some extent.
Photo is a web capture for explanatory purposes, copyright belongs to the company.