Yep, it does! And I went there today. It is a part of the rose garden, on the path up from San Niccolo quartiere to Piazzale Michelangelo.
The Japanese Shorai Oasis garden area was presented to Florence by its twin city, Kyoto, in 1998. The Japanese architect Yasuo Kitayama donated the garden.
The garden isn’t large, but it is nice.