Photo/IllutrationMen and women play mixed volleyball together. (Toru Nakakoji)

The ball is a bit lighter, jump serves are a no-no, and slightly relaxed rules allow for extended rallies.

Other than that, mixed volleyball is no different than the same-gender sport, and that's sort of the point.

Played by teams of three men and three women, mixed volleyball is growing in popularity for its compatibility with a gender-equal society and serves as a gateway sport to an active lifestyle.

The nonprofit Japan Mixed Volleyball Association held a national-level East Japan regional tournament on Aug. 11 at Todoroki Arena in Kawasaki, bringing together 15 teams comprising adults and students.

A world championship will also be held in Tateyama, Chiba Prefecture, in March 2020, adopting Japanese rules for the first time.

While spikes, which involve strongly slamming the ball onto the opponent's side, are typically the domain of male players, women on the opposing team could often be seen at the August event defending against the attack and smashing the ball through male players that were blocking.

Like the conventional six-player format, they rotate positions. However, the male and female players are positioned alternately on the court, with the front row changing from two men/one woman to two women/one man and vice versa.

"The real fun of mixed-gender sports is having men and women mixed together and coming up with a variety of strategies," said Yoshihiro Oe, 39, president of the association.

Volleyball is among the few sports in which men and women compete in the same event, joining mixed doubles in table tennis, badminton, tennis and a few others.

A former salesman, Oe founded the association in 2005. After his final competition as a member of a volleyball club at a senior high school in Tokyo, he formed a team so men and women in his hometown could enjoy the sport together. But with only a few competitions that they could enter, the team disbanded.

Oe decided to form the association because he thought his time would be more fulfilling with mixed volleyball.

Out of consideration for differences in the physical abilities among male and female players, jump serves and back attacks are not allowed. To prevent injuries, the surface of the ball is made from a spongy material, making it 20 grams lighter than regular ones.

Some rules are also slightly relaxed, with double touching and carrying the ball determined in a somewhat lenient manner to encourage keeping a rally going, while reaching over and touching the net are strictly banned to ensure safety.

After Oe started promoting mixed volleyball, he realized it would be easy for the sport to take root.

"It's difficult for single-gender teams to endure because of marriage, birth and child-rearing," Oe said. "It would be easier, however, for a team to continue when there are men and women on the team."

About 212 teams participate in local tournaments, which serve as qualifying rounds for the East Japan tourney. A combined total of 1,400 or so teams joined 192 tournaments hosted by the association at the national and regional levels for the year ending March 2018.

"(Mixed-gender volleyball) also contributes to the realization of a gender-equal society," Oe added.

O.N.F., one of the teams that competed in the eastern national tourney, is mostly made up of former members of volleyball clubs at J. F. Oberlin University and Nihon University.

"We can try a broad variety of strategies, as there are many areas (of the game) with no standards," said O.N.F. head Masashi Otsuka, 36. “It's also good to have a chance to play against women who have experience playing in the (top-level professional) V.League.”

Nagano-based club HP was established by a network of members of senior high school volleyball clubs in the city.

“At our club, women spike the ball and men go for a dig, a defensive move to prevent the ball from hitting the floor. We find meaning in the fun of such equality, and even losing can be enjoyable in such situations,” said Rena Kitazawa, 24, who restricts herself to the role of head coach because she is expecting.

The popularity of the sport is also spreading beyond borders.

Four years ago, Oe received an e-mail from Russia out of the blue saying that mixed volleyball is also played in the country and that Japanese players would be welcome to participate in a competition there.

A world championship for the mixed-gender sport has been held three times in Russia after the country reached out to the international community. However, under Russian rules, teams consist of four male and two female players.

The world championship to be held in Japan next March will be the first of its kind adopting the Japanese rules that require the same number of men and women on each team. Teams from at least 20 countries are expected to attend.