Perfected this after some tries:
For me the most difficult part is actually at the beginning; there is a stream of notes that alternates between single and hold notes that I find hard to get used to.
After that I just have to be careful. Because the most difficult part is at the beginning, I feel pressured throughout the song lol.
I gotta say, I like almost (if not all) the solo Rin songs featured in the series. Kokoro, Roshin Yuukai, Kodoku No Hate, Iroha Uta, Melancholic, Tokyo Teddy Bear and this.