C'est La Vie Oak Bottle
Fitting perfectly into the trend for aged cocktails, this American oak bottle lets you rapidly age your own booze. It’s super easy to use: just pour in your favourite booze and let it sit. The quickest oak aging process takes a mere two hours, although longer aging will mean more complex flavours. The bottle is also reusable: just rinse it with warm water and pop in your new liquor of choice.
selavi.co.jp/products/clv-298, available at most Loft or Tokyu Hands stores. From ¥9,000.