Wow, this really impressed me! I'm gonna sound like a jerk for saying this, but based off of the rather plain first impression with no title screen, no fanfare, just basic instructions given with boring flat text, I thought this was just gonna be a really generic and bad platformer using a vtuber to disguise it, to make it seem better than it is.
But boy, was I proven wrong: I loved so much of this! Once I started moving, I loved even the basic movement, especially the jumps with their satisfying shockwaves and bounce sounds. The animations in general were very cute and bouncy, with the standout being how Gura looks like she is being dragged by the trident when dashing. Speaking of, I liked the dash move and it's multi-purpose utility in that it not only carries you a long distance, but it also sticks into walls and lets you spring upwards (and I like the way you can tell if you can still dash by whether the trident is floating nearby). I specially love how challenging the levels got and how fast they did so: it really forces you to be creative and get good quickly at using the various moves effectively (and challenges you to collect the secrets as well)! I also love all of the hidden tech like momentum slingshotting by dashing into springs and gripholds, and how the levels are intentionally designed to force you into learning them in subtle ways. Only complaint I could really think is that it might be good if there was a save system, but nonetheless, well done, well done!