The 18-year-old was in stunning form as he recorded a score of 97.2 points to hold off home favourite Taylor Gold, while Totsuka's compatriot Ruka Hirano finished third with a score of 87.8.
And while it was only Totsuka's first triumph of the season it leaves him 400 points clear at the summit of the World Cup standings, leading Australia's Scotty James who did not compete in the US.
In the women's edition of the competition it was Chinese star Cai Xuetong who reigned supreme to make things interesting at the top of the table, registering a score of 94.8 to now sit level with compatriot Liu Jiayu on 3000 points.
Liu could only muster third in California as the USA's Maddie Maestro finished second, losing out to Cai by just 0.8 points to leave herself fourth in the overall standings.
And it appears something of a two-horse race at the top, with Spain's Queralt Castellet - who languished in fifth - lying third and 310 points behind.
Dusty Henricksen rose to the top of the leaderboard in the men's slopestyle World Cup with victory over both Ryoma Kimata and Justus Henkes.
The 16-year-old - who turns 17 on Sunday - had previously been trailing Henkes, but his superior haul by 400 points saw him usurp pole position.
Kimata is now ninth in the overall table, with third-place Vlad Khadarin languishing down in 32nd in California to leave him 194 points adrift of Henricksen.
And the USA's Jamie Anderson triumphed in the women's slopestyle event at Mammoth Mountain Resort, cutting the gap on overall leader Katie Ormerod to 1,000 points.
Great Britain's Ormerod finished third while Canada's Laurie Blouin scooped second, now leaving her trailing Ormerod by 800 points in the overall table.
The World Cup heads to Calgary, Canada, next time out on February 13, as Totsuka, Cai, Henricksen and Ormerod look to consolidate their positions at the top of the standings.