Those good feelings disappeared quickly, however, when Yairo Munoz hit Hirano's second pitch over the wall to key a five-run rally, which led to the Cardinals capturing the series with an 8-4 win.
"You feel like you have everything set up just the way you want it, with the back end of your bullpen ready, and Yoshi made a pitch and got clipped," D-backs manager Torey Lovullo said. "That's the nature of this game. It's a tough game. Yoshi's human. That's what it means. He has absolutely spoiled us. He's been a slam-dunk reliever, and he made a really tough game look easy for a long time."
Hirano's streak was the second longest by a Japanese-born pitcher, behind only Koji Uehara's 27-game run in 2013.
"It's good that I was able to do it, but it wasn't just me," Hirano said. "It was a team effort. There were other players involved."
After the home run, shortstop Ketel Marte committed an error and the inning spiraled out of control from there, with the big blow coming on Yadier Molina's three-run homer.
"It was almost like we played two games today, two totally different games," Lovullo said. "The first six innings were exactly the way you'd hope to see guys execute [and] go out and do their job. And then the final three innings, unfortunately, we couldn't execute in a lot of key areas, and you can see when you give an extra out or not making pitches to quality hitters, they're going to take advantage of it."
Adding injury to the insult of that seventh inning was an injury to center fielder Jarrod Dyson.
Dyson charged in to field Tommy Pham's single and, as he got to the ball, he appeared to pull up lame. He was removed from the game and, while Lovullo said a firm diagnosis had not yet been made, Dyson was experiencing discomfort in the right groin area.
"We're going to continue to look at him tonight and get him examined tomorrow by a doctor," Lovullo said.
The loss, combined with the Dodgers' 6-4 win over the Pirates, narrowed the first-place D-backs' lead in the National League West to one-half game over Los Angeles.
"Our bullpen's done an incredible job, so you know it's just a part of baseball," said outfielder Jon Jay, who had three hits. "Those things happen and we've just got to be ready for tomorrow."
MOMENTS THAT MATTERED Stranding them: The first two batters of the first inning reached for the D-backs and they would have the bases loaded with two outs in the inning, but were unable to deliver the knockout blow to St. Louis starter Miles Mikolas. It was a pattern that continued during the game as the D-backs left 11 runners on base and were 2-for-9 with runners in scoring position.
"We did a good job of fighting and grinding," Jay said. "But it was just one of those days where we came up short."
YOU GOTTA SEE THIS Trailing 8-4, it would have been easy for Jay not to try to make a spectacular play on Jedd Gyorko's fly ball in foul territory down the right-field line. But Jay never hesitated, and made a sliding catch up against the wall for the first out of the inning.
"This team doesn't shut down," Lovullo said. "They're going to go out and play and perform, despite any circumstances. We have smart players that want to play hard for all nine innings and that was a perfect snapshot of what we have here."
UP NEXT The D-backs open a four-game series with the Padres on Thursday night at Chase Field at 6:40 p.m. MST. Right-hander Shelby Miller (0-2, 11.42) will get the start for the D-backs. Miller is making his third start since returning last month from Tommy John surgery. The Padres will counter with lefty Eric Lauer (3-5, 5.08 ERA).