A merciful end to its regular season allowed Kailua to celebrate its bye-byes in style.

The Surfriders mercy-ruled No. 6 Castle 18-1 in five innings on Friday to clinch the East’s second seed — and a first-round bye — in the upcoming Oahu Interscholastic Association Red playoffs.

It made for a festive senior night at Kailua’s field for five departing players, including starting pitcher Bryce Ah Sam. The University of Hawaii-bound Ah Sam got a dream’s worth of run support as the Surfriders batted around in the first inning, scoring 11 times en route to by far their most productive game of the season.

Ah Sam pitched four hitless innings before giving way to reliever Iokepa Lapera in the fifth.

"We were aware of the fact that we were playing for a bye," Ah Sam said. "Just the fact of winning, it’s even more sweet that it’s on senior night … in the context that we get that bye."

He added an RBI triple in the third, making it 17-0. He didn’t allow a Castle baserunner until the fourth. He was all smiles between pitches at that point.

"I was just making the best out of my senior game," he said.

Sophomore left fielder Keola Himan led the torrid Kailua offense with three hits and five RBIs — four of which came on two hits in the first frame. Third baseman Wyatt Dalessio added a triple, drove in two and crossed home plate three times.

Kailua (8-4), last year’s Red champion, won its fourth straight to end the regular season. The Surfriders hadn’t cracked double-figure runs in a game before Friday.

"I think our team has been coming around," coach Corey Ishigo said. "You know, it took a little longer than expected. We’re trying to get ready for the postseason and we’re finally swinging the bats a little bit."

Castle (9-3) had already clinched the East’s top position and a bye going into the playoffs, making the game far more important on Kailua’s end. Coach Rocky Fraticelli was of a mind to rest his best pitchers in advance of the postseason. But the Knights went through three arms in the first inning and two more by the third as Kailua socked 10 total hits, several through the left gap, and patiently worked for walks.

To build on their stunning first frame, the Surfriders (and their vocal dugout) tacked on five more runs in the second behind Dalessio’s triple to left center.

Castle, down two starting outfielders because of injury, lost for the third time in five games after a 7-0 season start.

By the end of the second inning, the Knights had allowed double the runs (16) of their previous season worst.

"Awesome, awesome gamesmanship by Kailua. That’s all I got to say," Fraticelli said. "This game will turn out to be a blessing."

Castle got on the board in the fifth when Christian Kapeliela drew a walk and Andre Fraticelli knocked a double off Lapera to center field, followed by an RBI single by Alika Sakurai.