Suitability of a Laser dinghy for learning
About a Laser... it is NOT suitable for a beginner learning to sail. It takes a great deal of skill to sail one.
And Sasha, the Laser is one of the FASTEST single sail monohull boats in the world, capable of attaining enormous speed. With it''s round bottom and large sailplan, it has absulutely no form stabitlity, and it needs an agile crew to keep it on it''s feet. It is the sailing equivilent to a high performance windsurfer.
I would recommend that you look for a boat with a hard chine (when looking at the hull, you see a distinct line between the "bottom" and the "Sides") as they will offer a more stable ride. In the line of new boats, few manufacturers are doing this, as it is a more complex hull form to construct. They opt for the easy to mass produce rounded hull shape. Something in the 14'' - 16'' range, with enough room to sit IN the boat not ON the boat. This will aid in the veratility of your boat. Making it less of a "beach toy" and more of a suitable platform for adventures.
I always come back to the Sparkman & Stephens designed Blue Jay. But the supply of those may be limited in Tokyo. The Hunter 146 could work, and you can order them online for about $5,500usd. The Cataline 14.2 can even be had with a keel!
You may want to go over the the yacht clubs you mentioned and see what they are sailing there, as it would give you an opportunity to ask rig questions and get help from the folk there. It is always a good idea to sail something that has a local "Support Group" to help out during the early phase of ownership/learning.