Yoko Uozumi and her husband, Shigeru Otsuka, in Saitama, Japan. At the framing business where they both work, Ms. Uozumi, 36, uses the surname that she was given at birth. “I feel more independent,” she said. “I feel more who I am.”Credit...Ko Sasaki for The New York Times TOKYO — Japan’s Constitution promises gender equality, and Prime Minister Shinzo Abe says he wants a society where all women c