As for how she was chosen to perform in the event, it was because she met Philippine President Rodrigo Duterte during the time he visited in Japan when she was invited by the Japanese First Lady Akie Abe to perform during the President's Japanese visit. In the same interview, she also talked about how she learned Japanese as she's not a native speaker of the language as well how as she ended up having a career in Japan. Lastly, she hopes to release new songs in the Philippines.
From all of us here, congratulations!
[Source: CNN Philippines, One Music PH; special thanks to Jayson Bustamante for the tip!]