The government has been pushing for fathers to take paternity leave as Japan faces a demographic crisis, yet a new wrinkle has emerged: Almost one-third of mothers report that their partners do little to help out around the house while they're off work.

Of 508 mothers, 32 percent said their husbands did less than two hours of housework or child care per day during paternity leave, according to a survey released Wednesday by Mamari, a motherhood information portal. About 20 percent of the mothers reported that their husbands did more than eight hours of work.

The responding mothers said they often ended up doing housework themselves or that their husbands used some of the time to have fun.