There's this Chinese song 美丽心情.
I first heard of this song on radio in 2011. I liked the song but I didn't know its title, so I tried using TrackID on my phone to identify the song. TrackID is a music recognition service like Shazam. I still didn't know about Shazam at that time. TrackID identified the song title as 'By RuRu' and its artist as 'Harley and others'. The radio DJ also said that the song title is 'By RuRu'. Despite searching extensively on Google at that time, I couldn't find anything about 'By RuRu' or 'Harley and others'.
In 2014, I heard of the song again on radio. Once again, I used TrackID and it gave the exact same results. This time, I could remember a small part of its lyrics. I tried searching on Google for the lyrics, but I still couldn't find the song because the part I remembered was too short. Later in 2015, I came to know about Shazam which is better than TrackID, but I never heard of the song again.
In August 2016, I suddenly thought of the song and I was determined to find it this time. I tried searching for 'By RuRu' on Baidu instead. Then, I arrived at a Chinese forum where someone was also trying to find the same song. A person suggested that the song may be 美丽心情, but his answer didn't get any upvotes so I wasn't quite convinced about it.
Still, I searched for 美丽心情 on YouTube and I tried listening to it. Then, I realised that it's indeed the song! The singer of this song is 本多RuRu, so that's probably what 'By RuRu' is referring to. The TrackID team must have mistakenly recorded the song title as 'By RuRu'.
However, when I now use TrackID on this song, it correctly identifies the song as 美丽心情 instead of 'By RuRu'. Despite that, I am very sure it's the correct song, since I can still remember that small part of it when I heard it previously. It's a very nice song and I really like it. I'm glad to have finally found it after 5 years!