Warousoku are made of plant-based raw materials of haze seeds, rapeseeds, and coconut oil. The wick is made by wrapping dried material from a plant of the Juncaceae family referred to as 'lamp wick' around washi shaped into a cylinder.
This particular way of making the wick allows for air to pass up from the lower part of the candle through the wick's hollow centre, enabling the wick to absorb more melted wax, which in turn improves the brightness of the flame.
Warousoku (Japanese candles) were born in Japan through the introduction of Buddhism and date back to the Nara period (710-794 CE). In the Edo period (1603-1868 CE), the cultivation of haze (wax trees), a raw material used in warousoku, flourished in Kyushu and Shikoku, and these candles came into wide use by the masses.