The Pool at Hotel New Otani Garden Tower
Hotel New Otani Tokyo Garden Tower's pool is recommended by reviewers writing for major publications. Out of 7 professionals tracked on TripExpert, 4 endorsed the pool, like Rough Guide, Frommer's and Lonely Planet.
Hotel New Otani Garden Tower 
Rough Guide
Frommer's
Lonely Planet
Star Service
Rough Guide "a teaceremony room, art gallery, swimming pools, tennis courts and much more"
Frommer's "The large outdoor pool, shrouded by greenery, provides more privacy than most hotel pools and is free for members of Otani Club International (membership is free)"
Lonely Planet "Other pluses include an indoor 25m swimming pool as well as an outdoor one during summer months"
Star Service "Health facilities include a large, outdoor seasonal pool (a fee is involved for swimmers), outdoor tennis courts, a driving range, and medical and dental clinics"
