Kaze and the Wild Masks

This achievement requires you to earn a time trial medal on all regular levels and all bonus levels in the game (there are no time trial medals for bosses). While Golden Rabbit (10G) requires a gold medal, you only need one for that achievement (and the first level of the game is a piece of cake). On all other levels, at least a bronze medal is all that's needed for this achievement.

Time trials can't be attempted until you beat a level for the first time. Then, when you replay a level, there will be a purple clock right at the start. Grab it to start the timer. You now need to finish the level in a single run without dying, and fast enough to get at least a bronze medal. It should go without saying, but turn on Casual mode to make this way easier (so you can take two hits instead of one). There are no hearts in time trial mode, and no checkpoints, so you need to complete the entire level without getting hit more than twice.

I found these time trials to actually be pretty easy, with lenient requirements. I was able to get gold on most levels first (successful) try, and wherever I didn't, I got silver but a second or less. You therefore don't need to worry about any fancy movement mechanics or speedrunning strategies, thankfully. Simply moving through the stage as fast as possible is plenty fast enough to get a time trial medal.

One other nice thing about the time trial medals is that, like many good platformers that encourage speed, the levels are specifically designed such that, if you're moving fast/full speed, enemies and obstacles will line up perfectly so that you don't have to stop moving. You'll be able to spin under, jump over, bounce off of enemies as needed. Most obstacles will be lined up for you to keep moving. There were only a couple instances of "inelegance" where you need to stop before proceeding, but those will be obvious very quickly, such as icicles dropping on your head or green spikey guys being in your way.