findlestick | Castlevania: LoS - Music Box Skip (tutorial) @findlestick | Uploaded November 2017 | Updated October 2024, 1 hour ago.
Reference vid, most of the details are in the annotations (you'll have to excuse my crude scribbles). The blue rose can only be grabbed from underneath its room, trying to grab it from on top or the sides (while falling) doesn't work.

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Important: for the very final jump, as you attempt to grab the rose, jump towards the background.

Edit 1: At the end of the electric hallway, there's no need to hang off the ledge like I did. I just showed it that way to demonstrate what I'd be doing later on while on top of the final room. Jumping from on top of the electric hallway is fine.

Edit 2: The small platform underneath the final room is located directly below the ledge that you drop from.