The most common note in Project Sekai, all you have to do is tap when it reaches the judgement line! There are Blue and Yellow variants of the same note and the yellow one only grants more points and has the same mechanics as the reuglar ones.
The slider note in Project Sekai is almost identical to the one in Chunithm. The only diffrence is that with this note you have to release at the end of the note, meaning you can not leave your finger on the note at the end. There is also yellow and green varients of this note although they both still do the same with only a point diffrence.
The flick note is a note where you have to move your finger off the note quickly. It is noteworthy that the direction of the note does not matter as long as it is pointing up. This means that you can flick down and it will still register. There are also yellow and red variants of this note although again, it is just a point diffrence.