The CVD achievement won't unlock even if you follow the guide. The process is the same until you get the gas mask, but instead of moving the mouse to the right, move it to the left and immediately return your viewpoint to the toilet. Wait about a minute, and a code will appear under the gas mask. This should definitely unlock the achievement.

1ドルシミュレーターでCVDの実績をどうやって取得したか（これはGoogle翻訳です）

I see, I got one code for beating the game and tried Konami code, but thank you for responding