This narrow house in Osaka by Ido, Kenji Architectural Studio contains hollow white boxes for stairs and a skewed upper storey.

The three-storey house replaces the residents' former home on the same site, which suffered from a lack of natural light due to its proximity to the neighbouring buildings.

The architects increased the available light by rotating the second floor by 14 degrees, angling a pair of rooms towards a large corner window.

The rotation also creates voids above the staircases, which allow light to penetrate from the roof down to the lower levels.

Angular white boxes cantilever out from the wall to create sets of steps that appear to float upwards.

The main bedroom and bathroom are located on the ground floor, while the living room and concrete kitchen take up the first floor.

The angled second floor contains the children's bedrooms and has a tapered wall on one side to further open up the space.

The final staircase leads up to a roof terrace which is partially covered.

Other houses in Osaka we've featured include a building that cantilevers dramatically over its driveway and a house with a faceted concrete exterior.

We've also featured lots of unusual staircases on Dezeen, including one with floating wooden treads and a zig-zag handrail – see more stories about staircases here.

See all our stories about Japanese houses »
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Photographs are by Yohei Sasakura.

Here's some more information from the architects:

House in Tamatsu
The house is designed for 4 members of a family with two kids. The house is placed at urban district and a small plot of only 43.21sqm in Osaka, Japan. Around the site is the mixed-use area where small houses, small factories and small office buildings coexist together without any harmony.

The client’s former house, which stood at this site, was a wooden two-storey house. The adjacent sites were close and natural light didn’t enter into the old house. Therefore the client requested the family room (living area, dining area and kitchen) to be as large as possible without pillars or load-bearing walls, and that natural light that comes into the house, especially into the family room.

First, since the site was narrow, the volume of the building took up as much of the site as possible. According to the lifestyle of the client, the bedroom of the couple and wet areas were placed in the ground floor, the family room was placed in the first floor, the rooms of children were placed in the second floor and the terrace was placed on the roof.

For a structural reason, the large openings were not able to open out on the road side of the first floor of the building. So the architects rotated the volume of the second floor 14 degrees for the axis of the building, and interstitial spaces between the rotated wall and the outer wall of a building became voids.

The skylight was set up in the upside of the void, and is intended to allow natural light to drop on the family room of the first floor.

Site plan

Moreover, one of two walls rotated 14 degrees on the plan of the second floor is also inclined to the verticality, and the part which overlaps with the stairs is turned up and has become like origami or a facet. This inclined wall frees people's feeling by deviation from the norm, simultaneously the sense of touch of the degree of inclination and the light to reflect of that inclination causes a new physical sense.

Ground floor plan

The building's white box is completely different from the building of the neighbourhood. It is the appearance which the cylindrical volume of the second floor rotated 14 degrees penetrates into the building. Box-shaped cantilevered stairs are floating in the void.

First floor plan

Project Name: House in Tamatsu
Use: residence
Site: Osaka, Japan
Architect: Kenji Ido / Ido, Kenji Architectural Studio
Design period: March 2011 - February 2012
Construction period: March 2012 – July 2012

Second floor plan

Structural engineer: Masakazu Taguchi / Taguchi Atelier Planning Structure
Structure system: timber construction
Total floor area is 94.46 sqm.
Building area is 32.75 sqm.
Plot area is 43.21sqm.
Building scale: 3 storeys

Roof terrace plan