Secret auctions have been held for decades in Shinjuku, Tokyo, where people buy and sell babies. These exclusive gatherings accurately portray the selfishness and greediness of the various people who come to buy, or to sell. The film also focuses on minorities and the disabled who are championed by the Minister Machiko and the people in her orbit.
Machiko's son, Akira, and Toru, one of her political supporters, are lovers. These two brave young men have decided to undertake the first same-sex marriage in Japan, despite a rigidly enforced legal ban on gay marriage. They are guided through this political and emotional minefield by Masaru, a hard-of-hearing lawyer who stands firmly behind them. Masaru is actually Minister Machiko's son who had been given to his mother at one of the very early Midnight Baby Parties. The film ends on a high note, celebrating Japan's first gay marriage.