In its Dec. 20 issue, Asahi Shimbun reported on a couple in their 60s living in Saitama City. Two years ago their neighbor installed an Eco Cute system that uses heat pump technology to heat water more efficiently and, thus, reduce electricity costs. But since the system was installed, the older couple's health has been deteriorating, mainly due to loss of sleep. Eco Cute operates only at night, when electricity costs are low, and the couple claims that their neighbor's unit emits a low frequency hum, which keeps them awake. They sued the neighbor and the manufacturer of the Eco Cute unit.

In preparing the case, the couple's lawyer discovered nine similar suits. Moreover, the Consumer Affairs Agency received 40 such complaints in 2013, 50 in 2014 and 90 in 2015. More than 5 million houses have installed Eco Cute technology since it first went on sale in 2001, and until 2010 homeowners could receive a government subsidy since it conserves energy. Though the technology is good for homeowners and the environment, the noise problem seems real, but it has less to do with the technology than with Japan's housing situation. The plaintiff's bedroom is 130 centimeters from their property's border, and the Eco Cute unit is 65 centimeters from the border on the other side, meaning the problem device is only two meters away from where they sleep.

More than 70 years after the end of World War II, Japanese residential land size remains small in relation to the rest of the industrialized world, while houses get bigger. That means residential developments are even more cramped. Land prices are much less than what they were during the high-asset "bubble period" of the late 1980s and yet government statistics indicate that average land size for new housing lots continues to shrink.