Meaning of K4 is finally clear. It's been a rewarding challenge. I tried to express the mystery yet to be solved with cat illustration.

クリプトス・フォーラムに新しいメンバーが世界各国から加わって、活気付いてきた。クリプトス暗号が解読される日が近いかもしれないという期待感。暗号プロチームもがんばってます😀　私も新しい視点を見つけます😎

Kryptos' answer: Could it be the Statue of Liberty? Don't want a conclusion that's too far-fetched. I overthought it. https://onl.tw/BJBbsMC