reverse slope
https://gyazo.com/3a5411f791c6421d9f85ef4d260b401f
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This page is auto-translated from /nishio/逆スロープ. If you looks something interesting but the auto-translated English is not good enough to understand it, feel free to let me know at @nishio_en. I'm very happy to spread my thought to non-Japanese readers.