Named T Weekend Residence, the three-storey house offers residents various spots to read or dine amid a cool sea breeze, and even allows them to bathe with a view of rolling hills and a wide-stretching coastline.
"It is a playground for grownups to spend a luxurious time not possible in a city," said Process5 Design.
"One can enjoy a breakfast sitting on a swing, have a barbecue with friends in summer, read books covered in a blanket in autumn, or take a nap with a fire going in a wood-burning stove in winter," it added.
The 95-square-metre house is divided up into three storeys to make the most of a steeply sloping site. The upper storey forms the entrance, living spaces are on the middle floor, and the partially sunken lower level houses the bedrooms.
The building's volumes comprises a series of connected boxes, finished in a variety of materials. These include pale brickwork, white plaster, wood and concrete.
Inside, the open-plan living space takes up the majority of the middle floor. It includes a kitchen and generous dining space, and opens out to a balcony that spans the width of the property.
There is also a more private living area located on the bedroom floor, which can entirely exposed to the elements. It is here that Process5 Design added a swing and a brick cooking unit.
A bathroom sits in one corner of this space, offering views of the mountains and coastline through a floor-to-ceiling window, which wraps around a corner and can be slid open.
A narrow wooden staircase connects both of these floors with the entrance level, which features a large wooden roof terrace.
"Each floor is connected through this [staircase] volume, which deviates from the scale of a living room, and provides different view, light and wind environment," added the team.
Process5 Design was established in Osaka in 2006. The studio's past projects include a bridal shop filled with mirrored walls and picture frames.
Photography is by Keishiro Yamada/YFT.
Designer: Process5 Design
Structural architect: Euplan Sekkei