The official name is Kokuritsu Kasumigaoka Kyogijo Teikyujo, which is Kasumigaoka National Stadium Tennis Courts. One office runs two systems for use of 20 courts. These are separate from the other courts that are in the same general area and described in the Jingu Gaien Public page and Jingu Gaien Indoor page.
The ANNUAL MEMBERSHIP system covers 13 of the courts. 6 of the courts are in the West courts ("nishi" courts) just outside the main office; 7 of the courts are in the East courts ("higashi" courts) between the rugby stadium and the baseball stadium and have a secondary clubhouse attached. These 13 are hard surface. No lights. There is a changing room.
Annual membership is 94,000 yen for use all days, and 56,000 yen for use only weekdays. As of this writing there was a waiting list of about 20 persons, and new members are accepted only when previous members resign or don't renew. I was told that to work up through the list is "months, probably under a year". Lockers can be rented for 11,000 yen per year.
The hours of operation are 9 PM to sundown. From June 1 to August 15 you can play to 7 PM; this gradually shortens to 5 PM in February then lengthens again towards June.
The QUARTERLY LOTTERY system applies to 7 courts, of which 3 are are in the West court area ("nishi" courts) and 4 are next to the rugby stadium and are artificial lawn. You have to be at the lottery to participate in it. You'll be given a lottery number, then the numbers are drawn. The first number drawn gets first choice of two time slots in the coming quarter. Each time slot is 3 1/2 hours, either morning or afternoon. For group use the hourly rates are 2800 yen on weekends / holidays and 2100 yen weekdays.
During rugby season the 4 artificial lawn courts are pre-empted for use as warm-up areas by the rugby teams when there are games in the rugby stadium.
The lottery is held from 9:40 PM at the East court clubhouse. For Jan, Feb, March the lottery is on the third Sunday in December. For April, May, June it is on the third Sunday in March. For July, Aug, Sep it is on the third Sunday in June. For Oct, Nov, Dec it is on the third Sunday in September.
The closest subway station is Gaien-mae on the Ginza line. Take the smaller street that crosses Aoyama Dori, towards the Gaien complex of sports facilities. As you head north towards the National Sports Stadium, the West court clubhouse is on the left side of the street, about 5 mins walk and before you get to a small T intersection with a 7-story red brick building on the far corner. The courts are hidden behind white screening. The West clubhouse is a small two-story building. Ask here how to get to the East courts, which are hard to find.
There is parking in the area.
The address is Kita-Aoyama 2-8-37 (East court clubhouse) and phone is 3408 4495. Closed on the 2nd and 4th Tuesdays of each month.