A bedroom and bathroom are hidden inside a white box in this converted warehouse by Japanese architects Airhouse Design Office (+ slideshow).

Located in Yoro, a small town in Gifu Prefecture, the main space of the house is on the first floor of the converted warehouse, accessed via a staircase inside the ground-floor garage.

Airhouse Design Office inserted a large white box in the centre of the space, creating private rooms inside and a loft above.

Designed for a couple who are keen on cooking, the focal point of the house is the large kitchen.

The kitchen units were made from ash, while artificial marble was used on the worktops and table.

To minimise heat loss in the large space, a thick layer of urethane foam was added to the walls and ceiling before they were covered in plywood panels.

The loft is accessed by a wide white staircase and used as a children's bedroom.

Inside the box is the main bedroom, painted a deep shade of purple, a lime green bathroom and a separate toilet.

Airhouse Design Office was founded by architect Keiichi Kiriyama in 2009 and is based in Ogaki, a city in Gifu Prefecture.

Other houses in Japan we've featured lately include a building based on the Fibonacci mathematical sequence and an extension featuring tree trunks that stretch from floor to ceiling– see all Japanese houses.

Photographs are by Toshiyuki Yano.

Here's some more information from the architect:

House in Yoro

One of our client's major requirements was for a living space where the presence of the family would always be felt. In response, we devised a single-room layout without columns that took advantage of the distinctive features of the existing warehouse.

A large kitchen was installed to cater to the needs of the food-loving husband-and-wife couple. We then conceived the entire living space by taking the kitchen as a focal point, with a mix of various other activities and functions unfolding around it.

Within this single-roomed space, we also created a box-like structure with a loft bedroom for the children on top of it, and private quarters including a bedroom and bathroom inside it.

In order to minimize heat loss within this massive space, a 100mm layer of urethane foam was added to the walls, floors and ceiling, while a combined heat and power device was installed in the living room to heat water and provide floor heating.

All openings were designed by making use of existing sash windows and doors, while glass panes were all given a double-glazing treatment to improve insulation.

The façade of the building was left intact in an effort to blend in with the surrounding neighborhood, as well as due to cost considerations.

Above: ground floor plan

The result was a comfortable, luxurious home that made effective use of existing features while also avoiding excessive expense.

Above: first floor plan

Location: Yoro, Gifu
Date of Completion: May 2012
Principal Use: Private House

Above: mezzanine plan

Structure: Steel Frame
Site area: 1027.34 sq m
Total Floor Area: 131.58 sq m

Above: section

Above: section