The same tea, made with the same leaves and the same water, can produce very different results depending on the utensil used. The kyusu teapot, in particular, was designed in Japan to best complement the expression of green tea.
The difference lies largely in the freedom given to the leaves. In a kyusu, they have ample space to fully open, unfurl, and circulate in the water. This allows for more even contact with the water, resulting in a richer, more nuanced extraction. The tea gains depth and balance, with a more pronounced presence on the palate.
Conversely, in a cup with a filter or in a tea ball, the leaves are often more restricted. Their opening is partial, their movement limited. Infusion is still possible, but it is generally lighter, sometimes less intense.
The act of serving is also part of this process. By slightly tilting the teapot, you set the leaves in motion and guide the infusion to completion. The idea is to extract every last drop of tea, which often concentrates the most intense aromas. This technique allows you to reveal the full richness of the tea without losing any of it in the pot.