It was when I review my comment again that I found I pressed the key 2 rather than 3 by mistake( when recovered in the guest room of the mansion I recognized the 3 branches for each routine, and I tried each one shortly for a while, yet I didn't predict they will lead to different ending).
However, during the process I hadn't found another choice which could influence the storyline, so the pre-condition of "the true Reimu ending" is to finish all the 3 endings? (After the final boss battle, Reimu and the other two went through a door, then fight with Tokiko for saving her, I do wonder is this part the true enging, or just a normal content of the whole game? If not, could u please provide some tip of the true ending?)
Thank you for your patient reply(゜▽゜*)♪