Morikawa carded a closing 69 at The Concession Golf Club to finish 18 under par.
The golfer previously said he was in ‘good spirits’ after being moved to a second hospital in Los Angeles.
England Rugby has called for "true rugby fans to stand with us" after players were abused online in the wake of Saturday's Six Nations defeat to Wales in Cardiff. England prop Ellis Genge revealed he had been subjected to death threats after footage surfaced of him apparently neglecting to clap the victorious Welsh players off the pitch following the match. Genge wrote: "Don't know why I'm not clapping in that tunnel, must be deep in thought - utmost respect for the Welsh, as for keyboard warriors sending death threats etc..."