Guardians of Another World

Guardians of Another World (異世界の守護者) is the twenty-fourth episode of The Rising of the Shield Hero anime.

Synopsis
Melromarc brings a large fleet to fight the Wave out at sea. While the queen takes charge and leads the operation well, the other three heroes prove useless yet again, leaving Naofumi to do it all alone. Later, he gets help from L'Arc and Therese to fend off the monsters, but then...

Plot
After finding Cal Mira Island's underwater Dragon Hourglass telling that the next Catastrophe Wave will strike in 2 days, Naofumi, Raphtalia and Filo rushed back to Melromarc (via Teleportation skill of the Shield) to alert Queen Mirellia and Princess Melty. The next Wave is sure to be occurring at open sea, so both Mirellia and Melty are already aboard battleships on their way to fight with their countless Knights and the other three Heroes with their respective parties (with the Sword Hero being oddly frightened to fight, perhaps due to sea-sick sensation). Melty came along because she feels like being part of Naofumi's group, much to Filo's joy. Queen Mirellia adds that Earl of Habenburg had already had Cal Mira residents safely evacuated beforehand. Even with this imminent threat, the other Heroes still refuse to teamwork, believing that their individual level-up will be enough. Raphtalia sees that L'Arc and Therese are also coming to fight, both whom Naofumi regards as being far better than the other Heroes, but the redhead guy strangely decides to ignore Naofumi.

The Wave strikes, teleporting everyone to it. The Knights deploy lucor fruit barrels into the ocean (the alcoholic effect will help stunning the monsters) and fire arrows to bring out and kill the numerous acquatic enemies. The boss monster, a gigantic narwhal-like creature, shows up. Itsuki fires a Meteor Shot, but it deals no damage. Ren states that it can only be effectively attacked if lured out of water. Naofumi and Filo dive into the water, by Mirellia's request, to draw out the monster; the Soul Eater Shield uses Hate Reaction to attract the foe and force it to jump into open air. The three Heroes use Meteor Shot, Meteor Thrust and Meteor Slash, but it didn't even scratch the monster. The creature attacks with a powerful laser from the crystal on its forehead, destroying one of the ships. Using a harpoon launcher from one of the ships, Raphtalia fires a magic harpoon which pierces through the monster's head, thanks to her own level-up. The smaller fish-like monsters start invading the ships, but Melty's Zweite Acqua Shot quickly makes short work of them. One of the monsters stealthily snatches Melty and tries to drag her into the sea, but L'Arc saves her right in time. He unleases a Skybound Wheel Swing to get rid of more monsters. The Knights and ships crew keep deploying arrows and lucor fruit barrels into the sea. Melty suspects of L'Arc distaste when she mentions Naofumi. The Shield Hero and Filo once again bait the narwhal out of the water; L'Arc and Filo attack with Skybound Wheel Swing and Spiral Strike; Therese's Bejeweled Thuderstorm combines with L'Arc's Scythe into Combo Skill: Thunderstrom Wheel Swing, finishing the monster for good. The other Heroes come to pilfer the drops from the slain monster but are belittled as "weaklings" and rapidly repelled by L'Arc, who reveals that he wants to kill the Shield Hero for the sake of his own world.

Though they have nothing "personal" against Naofumi, L'Arc and Therese reveal they are also Heroes, from another world which was also on brink of destruction due to the Waves. Mirellia and Melty declare them to be the enemy and order the Knights to help the Heroes against them. The Knights and even the Heroes prove no match for the two adventurers. Therese summons a Bejeweled Meteor Shower to non-lethally neutralise the Queen's forces and a Bejeweled Silver Lining to "protect" Naofumi's party from it, so they can fight without interference. Therese asks Raphtalia and Filo to stay out because only Naofumi is the fight target, but the two girls decide to fight anyways. L'Arc lunges at Raphtalia, but the Soul Eater Shield bites his right arm. Queen Mirellia orders to rescue the Knights and crew while Melty demands Rishia to take her to where Naofumi is. Naofumi blocks L'Arc's Scythe but feels his own right arm hurt; Therese fires a Bejeweled Sin Flame which oddly dissipates before hitting Naofumi. They hear a voice in sorrow, which comes from the bracelet Naofumi has crafted for Therese, "refusing" to go against him. Therese decides to switch bracelets, and L'Arc explains his physical strike deals damage in direct proportion of the target's defense, thus being "perfect to use against the Shield Hero". Naofumi gets irritated that L'Arc is always one step ahead of him everywhere during their trip. Melty arrives to help. Instead of feeling cornered, however, Naofumi feels confident that his Air Strike Shield and Second Shield will render L'Arc's attacks useless. The two parties clash furiously with several strikes from both sides; Filo's and Melty's Typhoon pushes L'Arc backwards into Air Strike Shield, and Raphtalia's sword injures his left arm. The two parties compliment each other's strong points, and Naofumi starts acknowledging L'Arc and Therese as real Heroes from their own world.

Suddenly, a female voice launches a powerful attack against one of the remaining ships. Naofumi recognises an old enemy, Glass, standing beside L'Arc and Therese. She launches Zero-Stance Rondo: Reverse Four Seasons and Rupture-Stance Rondo: Tortoise Shell Cracker, both which Naofumi can barely contain. Glass explains that Naofumi was not even fighting with his full power and managed to fight toe-on-toe with and hurt L'Arc substantially. The Shield Hero stands ready to fight the raven-haired woman again as she proposes to take him down personally.

Light Novel & Manga Differences
Melty participates and helps Naofumi in the battle. In the manga she stayed in Melromarc.

Trivia

 * The Queen directly aids in fighting the Wave, similarly to how she helped fight against the Pope.
 * Melty reaffirms herself as member of Nafoumi's party and aids him in the fight.
 * Cohol fruit in barrels are used as cask bomb in the sea.