Very professional and well organized wedding venue. We held our ceremony, lunch and reception party here. It can be pricey, but not nothing in Tokyo is cheap.
We changed our mind about guest numbers and increased the reservation by 30 people. We were charged 50,000en for changing our mind on top of the extra headcount prices.
That aside, I would recommend Happo-en as the service and quality is second to none. Just be sure of what you want and be prepared to negotiate.