Designed by Tagami Haruhiko and build by his company 木製キャンピングトレーラー　タイニーハウス – タイニーハウス ジャパン　tiny house japan (Instagram)

Tiny House Talk: Man in Japan Builds Micro DIY Tiny House on Wheels

Living Big In A Tiny House: Breathtakingly Beautiful Japanese Tiny House on Wheels

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See also 内藤千紗子 channel on YouTube.
Slightly related: Oregon Cottage Company – Tiny Tea House (via)