Taylor Ward homered and drove in four runs, and Los Angeles scored 11 times in the third inning to beat Oakland 13-1 on Saturday, spoiling Fujinami's major league debut.
Ohtani added two hits and two RBI for Los Angeles. Gio Urshela, Jake Lamb and rookie catcher Logan O'Hoppe drove in two runs apiece to help the Angels avoid an 0-2 start for the second consecutive season.
"I'm not worried about the offense," Los Angeles manager Phil Nevin said. "You go back and look at the tape (from Thursday), we hit some balls hard and things could have gone different ways. Happy with the way they swung it today, and we pitched well and played really good defense."
Angels starter Patrick Sandoval (1-0) gave up a home run to Ramón Laureano, but that was it.
Fujinami, who signed a one-year, free-agent deal with Oakland after spending the past 10 seasons with the Hanshin Tigers, was part of the same draft class in Japan as Ohtani in 2012. The right-hander breezed through the first two innings, then fell apart.
After getting Ward to strike out swinging at a 93 mph slider to begin the game, Fujinami (0-1) whiffed slugger Mike Trout swinging on a 95 mph slider and got Ohtani to ground out weakly to first base.
Following a 1-2-3 second, the Angels broke through in the third. O'Hoppe's RBI double got it going. Ward had a run-scoring single before Ohtani banged an 0-1 pitch off the left-field wall for a long RBI single.
Anthony Rendon added a sacrifice fly before Lamb's two-run single made it 6-0 and ended Fujinami's afternoon after 55 pitches.
Ward's homer was a three-run drive off reliever Adam Oller.
"Definitely the start we needed," Ward said. "Just bringing the fire like that, we need to do that every game. For me, I was just trying to really stay on (Fujinami's) heater. In the situation I was in, with runners on, I figured he may go to an off-speed pitch early on, so I was ready for it."
Fujinami lasted 2 1/3 innings, allowing eight earned runs with three walks and four strikeouts.
"The first inning the fastball was working very well. I thought the third inning I threw too many off-speed pitches. I should have thrown more fastballs," he said through interpreter Issei Kamada.
Fujinami was quick to point out he's not satisfied.
"Just getting on a big league mound is not enough," he said. "I'll probably think about it when I get back home, but today's today. Tomorrow's a brand new day."
Sandoval allowed two hits in five innings. He struck out two and walked two. In nine career starts against Oakland, the left-hander is 3-3 with a 1.84 ERA.
"I'm just trying to keep my foot on the gas and make pitches," Sandoval said. "Made some pitches but also didn't make some pitches."
Tucker Davidson pitched four scoreless innings for his first major league save.
It was the fourth time in the last 50 years the A's allowed 11 or more runs in one inning. ... Oakland shortstop Carlos Perez singled in the ninth in his first big league at-bat since 2018. "Congrats to Carlos for getting that hit after not being here for five years," A's manager Mark Kotsay said.
Angels: Brandon Drury was given a planned day off. Lamb started in Drury's place at first base and batted sixth. ... Rendon, the subject of an ongoing MLB investigation after an altercation Thursday with an Oakland fan, was removed in the bottom of the sixth after running into a rolled-up tarp in foul territory earlier in the game.
Tyler Anderson makes his Angels debut Sunday against Ken Waldichuk in a matchup of left-handers. Anderson had a 1.35 ERA over 13 1/3 innings this spring. Waldichuk went 0-4 in five starts last season for Oakland.