Do you want to go there with mext or on private funding?
So long as you explain things the way you did here, i don't think it will be a problem. You'll have to take the same exam as everyone else, though, which is what makes tokyo so competitive.
My best advice ==> If you want to work in finance in HK or Singapore, you should network with 10+ people on the ground in Asia to get their views on your background, your plans for a Masters degree in Tokyo, and your plans to work in Asia. Use your work and university alumni databases; use linked-in. Get on the phone now.
Other observations ==> A few years back, an economist with a with a PhD from Harvard (who became a close friend) provided me some career advice that you may or may not find useful. Use it as one data point rather than gospel.
He noted that PhD track economics was extremely quantitative and strongly favored students with deep math skills; most everyone else just got left in the dust. His thought a masters degree in economics was not a particularly useful degree because many economist-employers just saw that as a failed PhD effort (which he said was often but not always the case). This was further compounded by the large number of economists vs limited number of good jobs, making for challenging job prospects for the economist with the masters degree. His strong recommendation to me was a good MBA. He strongly recommended against a masters degree in economics but said a strong PhD would open doors in a very competitive job market.
I think your engineering degree, MBA, CFA certification, and bank experience are credentials enough. Will another Masters degree make that much of a difference? Importantly, the finance and job markets will be at a different part of the cycle (better?). And you will be 3 years older, which matters to some people, unfortunately.
Also note people in Japan generally hold an undergraduate degree from Tokyo U in high esteem. Many of my Japanese friends have mixed feelings about various Tokyo U graduate degrees, however. I don't know the reputation of UTIPE in Japan or in Asia.
Finally, as you alluded, getting a good job in finance in Tokyo is difficult. The language barrier is a major issue. And most major international banks and asset managers have rebalanced their staff to other Asian countries (Partly due to the rapid growth of China and Korea, on a relative basis).