Mitsuko Kobayashi often gave blood at local Red Cross centers as a young girl, because her mother said she should try to help people. But after giving birth two years ago, she found such trips difficult with a child in tow.

Then a year ago, while shopping in Tokyo's Kichijoji district near her home, Kobayashi, 34, came upon a center that cared for children every Tuesday while their parents donated blood.

The center is among a growing number offering extra, even trendy, features to attract donors, especially younger ones at a time when donor numbers are falling.