Weekday mass (Monday to Saturday) am 7:00 at the underground chapel First Friday mas (every first Friday) am 10:00 at the underground chapel Load’s day mass Saturday 18:00 at the underground chapel Sunday 8:00 and 10:00 at the Cathedral 10:00 at the underground chapel

I cannot be precise about opening hours but being a church I think you could safely say 9.00 to 5.00. there appears to be administrative staff working there who have offices within the cathedral building. It is open at weekends but there was a wedding in the afternoon on the Saturday I went there and on Sunday there are likely to be services. John

The train doesn't actually make it all the way to the Cathedral. It's a train and bus affair. Take the Oedo line to Ushigome-yanagicho then walk down the hill and take the bus at the intersection at the bottom of the hill. Stay on the same side as the railway station. Then take the bus about 6 stops to the Hotel Chinzans. The cathedral is opposite.