First I want to apologize.
I don't know if it is appropriate for me to submit in English here, but I don't understand Nihongo, so I can only try to express my questions and ideas in English.
I first came into contact with Kiyohiko and his singing on YouTube a few months ago, and was immediately conquered by his charm. Now I must watch Kiyohiko singing on YouTube every day.
Because I am not Japanese, I paid special attention to the English songs sung by Kiyohiko. Many of them have been favorites and familiar to me since I was young, such as Green Green Grass of Home, Love is a Many Splendored Thing, etc.
I think Kiyohiko surpasses the original lead singers of these songs, such as Tom Jones, Engelbert Humperdinck, Andy Williams and others, in terms of English pronunciation, singing skills, song interpretation and expression. The most representative one is the song Till.
I'm curious, are both English and Japanese native to Kiyohiko? Because the pronunciation of the English songs he sang was standard, there was no accent at all, and there were no flaws in the syllables.
If English is not his mother tongue, are the hundreds of English songs he can sing the result of his own practice? Because I noticed that some songs, such as Love Me with All of Your Heart, the version that Kiyohiko sang when he was young and included in Golden Best, had a very slight accent, but when he sang it later in public performances, there was no accent at all.