This is probably one of the easier non-story related bronze trophies, you can go to a Karaoke place whenever available and just simply do all 6 songs, and it'll be yours.
I obtained this in the Karaoke place in "Kamurocho", so find where this is, go onto your Pause Menu
> for "List"
> Then keep scrolling until you find "Karaokekan Kamurocho"
and it should show you the location (Which is the bottom right of the map).
It'll cost you 500 Yen to go inside and do 1-2 songs so it's very cheap, and as said previously there's 6 songs total, and you can do all of the songs in the one place with no catch, the following songs are: I Wanna Change
, Summer Memories
, Saturday Night Lover
, Kamurocho Lullaby
, Where Has Your Touch Gone
, Shooting Star
As for the songs themselves, what I did is start up the song and not even pay attention and press buttons, as I wasn't particularly fond of this mini-game, it doesn't matter what you score or if you even score, as long as you start up the song and it gets to its finish, it counts. In the menu of choosing song it should say "Times sung" at the bottom, if it's 1, then it's good and you can go onto the next.