I have visited this church thanks to my first guide of Tokyo Architecture by J.Vorrall.
At that time I was equipped with an fresh English map of Tokyo and lot of energy. I woul have waoke up early and catching a series of subway to get in the designated area. Then I was normally walking over and over to l0ok for places spotted in some books. Two guides were my first ones, one from Vorral the other from the 80ies written in italian, wasa broader guide since went back to the beginning of the century.
At the end of the day I would have walekd from 7 to 10 kiometres, and coming bach home with hurting feet, usually.
The interesting thing of the roof is that is formed by prefab concrete bricks, overlapping each other to form the arcs. or crossing vaults. Very impressive from down.
I followed inside a Christmas Ceremony and the baptism of new catcholic adepts.
It is located in the heart of the Korean town of Tokyo. near the station of Shin Okubo. I did not know there were so many catholic in Korea!
Here is the offical church web site.
In this blog other pictures.