With a 3-hour meditation course under your belt, perhaps you’ll be ready for a longer and more intensive meditation retreat on your next trip. Many Buddhist temples in Japan provide 8-day intensive retreats several times a year with eight or more hours a day of meditation conducted several times a year for the training of their resident monks and also for interested lay people. If eight days is too long, some offer shorter retreats. The retreats are inexpensive (some temples only ask for a donation) and you’ll sleep on a futon on tatami mats in the same room with others. You’ll get up around 5:00 a.m. to chant and meditate and perform various chores throughout the day such as picking weeds out of the temple’s moss garden, sweeping leaves, etc. Temples that offer these retreats are scattered throughout Japan and some of the temples and their gardens are exquisite. The food will be very good, and you’ll have a more memorable stay than you’d have at any Aman Resort in Japan for a fraction of the cost. https://medium.com/@ellenlouisefreem...n-1dbdc7eeca4f
Perhaps you knew this and were just offering other alternatives to Zazen, but since the OP is asking about Zen Buddhist meditation, I should mention that Tenrikyo is not a Buddhist sect, so they would not offer Zazen mediation courses or retreats. It is classified as a “New Religion” in Japan and was originally considered a sect of Shinto, but today, it is organizationally separate from it. Years back, there used to be numerous palm reading stands in Ginza (and around Tokyo and in other cities as well) and some of these palm readers are members of Tenrikyo, as palm reading was one way they recruited new members by telling them they could reverse any bad fortune revealed in their palm by practicing this religion.