Let me preface this post by saying that I am new to this board, but also that while I am female, I am not Japanese. However, here is my tuppence on the matter.
I agree with Ww in his explanation of why young women tend to keep to their age range. May I add, that it wasn't until I was near the end of my undergrad degree that I began mixing with people outside of my age group. Nearly all of the older-than-me gentlemen I met were either professors or parents, neither of which are particularly date-able. It would not be difficult to believe that you are being, perhaps unfairly, lumped into this group in their minds. Additionally, from what you have told us, you do sound nice of paper. Alas, young women are often not looking to find a husband and get married straight away. In my experience (though this might be different in Japan) young marriage is a result of falling in love first. I would focus on being a good date before being good marriage material.
My advice to you is to cold approach as many women as possible. Start with something innocent such as "Excuse me, could you tell me if there is a nice coffee shop near here?" and then maybe offer a compliment such as "You have very beautiful eyes" and then invite her to join you. Be well dressed and good mannered and results should follow. Do not approach a woman with headphones or who is in a hurry, they are not interested in being approached at this time. During the coffee date focus on her interests and try to work what you have to offer into the conversation. Focus on what you can offer short-term as long-term can be a little overwhelming at first.
Lastly, referring back again to Ww's post about being outside of their dating pool, let me add that it is likely that you will need to approach a lot of women. Do not despair, it often just comes down to a numbers game. The psychiatrist Albert Ellis famously approached 100 women on park benches yet only came away with one date (who stood him up). As your details seem a lot more appealing than his were at that time, I'm sure you will do a lot better, but do be realistic.
For a woman, you have a nice grasp of boilerplate PUA language, as well as a strangely familiar writing style...
NICE!