Keiō Mogusaen is a garden with a history dating back to the early 18th century, and it's a popular spot in Tokyo to celebrate the best of plum blossom season. The garden grounds are home to somewhere around 500 plum trees, and their hilltop location means that visitors can also get some great views out over the surrounding area on their visit.
When the blossoms are looking their best, a festival is held to celebrate their beauty – you can expect it to run from early February until early March based on previous years, but do note that depending on weather conditions there can be fluctuations to the exact dates. There is an admission fee of 500 JPY for adults and 100 JPY for children to access the garden.