The ground floor of this Osaka home by Japanese architect Masatoshi Hatamoto is sunken below street level to create more privacy for its residents (+ slideshow).

Hatamoto and his studio Flame Planning Office designed the family home for a neighbourhood characterised by its mixture of new and old houses. Because of the natural slope of the land, many of these existing buildings sit lower than the road, so the architect followed suit.

Named House of Yabugaoka, the new two-storey residence has approximately a third of its volume set below street level – a move that also creates a secluded garden at the building's entrance.

"I looked for the way to defend privacy against a problem in these sites – the look of the person who walks along a street," explained the architect.

"I consider the space here to have a feeling of liberation. By utilising the difference in the height of the southern road and the site, a space where the family can gather is made."

The building has a simple timber frame. Most of its exterior is finished with a dark brown-toned render, but it also has a facade of wooden louvres, helping to further maintain the residents' privacy.

These are arranged vertically, flanking a balcony and a wall of glazing to one side of the first-floor hallway.

"The deck enclosed by the wooden louvres is here to divide outside and the interior," said Hatamoto. "This will be a buffering area for the eyes."

The front door is glazed to make it appear more welcoming. "It gives a light sense to the building from outside," said the architect.

Inside, the building has an area of 115 square metres. The main family living room is located on the sunken ground-floor level, with the dining space and lounge at the front, and the kitchen at the back.

A range of materials and surfaces help to define the different areas. The kitchen features concrete and tiled surfaces, with grey as the predominant colour. The lounge and dining area both have wooden flooring and white walls, but are differentiated by varying types of window.

A double-height space on one side of the room accommodates the staircase – a series of flat wooden treads slotted into a zigzagging metal frame.

Upstairs, there are three bedrooms and an additional guest room. One of these is the master suite, but the others can be easily repurposed when a study or playroom is required.

Photography is by Yohei Sasakura/Sasa no Kurasha.