I got off at Harajuku to walk over to Tokyo Mosque. It seemed like a straight shot from Harajuku and I had a map so it didn't look too complicated. Unfortunately, I got a little confused so a nice Japanese man asked if he could help. I showed him where I was trying to go on the map and he seemed concerned and said it was far and probably best to take a taxi. I followed his advice and got in the next taxi I saw. I showed the nice taxi driver the map and he said he knew exactly where it was and that it was no problem. I felt so relieved and just relaxed. After a few minutes, the taxi driver stopped and pointed down a small road and said it was just down there. I thanked him profusely and got out of the car. However, looking down the road I didn't see the mosque. I asked another Japanese person who was passing to show me where I was on the map. He pointed to an area off the map!!!! I was totally shocked. The taxi driver had only driven me a few blocks and had even taken the money as if he had taken me to the actual place! Based on the map, it looked like it was just a little ways up the street so I set off walking. After about 10 minutes of walking, I sighted the minaret. After another 10 minutes I arrived in front of the mosque. (I was still annoyed at the taxi driver because if he had just driven another few minutes up the street we would have been there.)
Upon entering, there was a nice, friendly man inside who spoke English and said it was fine for me to have a look inside the mosque. (I had a shawl with me to cover my head, women cannot enter without covering their hair.)
It was beautiful inside the mosque and truly peaceful and serene. Many people were inside praying, relaxing, and even sleeping.
Later, I spoke with some Palestinians who related that they had similar trouble in finding this mosque. They told me they had asked several policeman for help in finding the mosque to no avail. It also took them a long time to find it.
It seems that for finding mosques in Tokyo, your best ally is a map rather than asking for help.