Do you need a triangular corner for the kitchen sink anymore? I found a product called "self-supporting drainer garbage bag" at the 100-yen shop Can Do, so I bought it.
This "draining trash bag" is a solid polyethylene trash bag. There is plenty of gusset, so you can stand it in the sink as it is.
Compared to the net type garbage bag, the drainage of water seems to be a little less, but it seems that there is no problem if you squeeze the bag before throwing it away. The approximate size is 180 mm long x 250 mm wide, and the gusset is 120 mm. The price is 108 yen (tax included) for 15 pieces. If you are thinking "cleaning the triangular corner is troublesome" or "want to reduce the feeling of living in the kitchen", why not use it?