torch, signal fire
炬 centers on a portable open flame used for light or signaling: a torch or signal fire.
炬 combines 火 (fire) with 巨, which likely contributes the sound. The character expresses a fire-based light source such as a torch.
Fire 火 beside a giant 巨 shape: picture a giant torch blazing, used as a signal fire.
For コ, imagine a small child holding a torch: 子 (こ, child) -> コ, and the child waves the signal fire.
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kotatsu; table over an electric heater, with a hanging quilt to retain heat (orig. over a charcoal brazier in a floor well)
kotatsu not put away but used in spring
torch
pine torch; torchlight; firebrand
square latticed wooden frame for a kotatsu
(electric) kotatsu table
futon or cloth attached to the kotatsu's frame; cover for kotatsu