Gotenyama Garden (御殿山ガーデン) is very close from Shinagawa Station. It is a very small garden, but very quiet and relaxing.
Tourist info:
Gotenyama Garden is a garden located within the Gotenyama Hills. In the hills, there are hotels, restaurants, offices and shops. The place is very little known by non-locals, so there usually are very few people in the garden.
Access:
0. at Tokyo Station
1. use Yamanote (JR) to Shinagawa (12 min.)
2. walk south (12 min.)