Konosuba. Devil King Kazuma Gaiden

Tales of an Archpreist. Keele's dungeon

Cecily was a devout follower of Axis Order, but she also had a secret desire for adventure and excitement. She was impressed with Kazuma's group and their accomplishments, and she wanted to experience the thrill of fighting the Devil King herself. Kazuma initially hesitated to let Cecily join, but eventually agreed to test her after seeing her determination.

The receptionist Luna told Kazuma and his group that they discovered a new passage recently in a beginner dungeon known as the Keele's dungeon. The dungeon was made by an ancient warlock to keep his enemies away, so the Guild thought on Kazuma to search anything of value there.

Darkness went to Belzerg to appeal for the return of Kazuma's holdings from the now defunct Alderp, requesting Balter, Alderp's son, to support her motion and Megumin went back to the Crimson Demon village to see her family, so Kazuma had no choice to let Cecily accompany him to the new section of the dungeon.

According to the legends, the dungeon was made by the greatest Arch-Wizard in the kingdom who turned into a Warlock. That prompted Kazuma and Cecily to take precautions. Kazuma turned his ring Draupnir into a spear and since Cecily was compromised with Kazuma's group, Kazuma decided to give her a tool in order to improve her Archpriest powers. Kazuma used his Forge ability to make beautiful holy earrings that enhanced her archpriest skills. Kazuma called it "Airmid's Blessing"

Cecily felt a little sacrilegious for using earrings that didn't carried Aqua's name, but Kazuma reassures her that Draupnir and the weapons and equipment he makes are indirectly bestowed by Aqua. Both of them entered the dungeon and found the unexplored passage. Carefully they entered the passage. As they went down, a creature attack them. Kazuma didn't squander any moment and killed the creature. Cecily explained that the creature he killed was a low-class demon called gremlin.

Kazuma let glowing pieces of Draupnir copies that they could follow to getting back. They found some treasures but nothing too big. Cecily sees an unopened chest and was about to get it, but Kazuma stopped her and tosses his spear at the chest. The chest begins to bleed and showed it's true form before expire.

Cecily tells Kazuma that the thing he just killed was a Mimic. A shapeshifter that lures people to it before swallow them whole.

Several undead enemies appeared to fight them, but Kazuma used Draupnir as a light spear to skew their necks and behead them while Cecily used her newfound powers to imbue holy power hin her hands to hit and destroy the undead while she recited mer mantra "Eris pats her chest" multiple times. Little did they knew is that someone was watching them and was very interested in Cecily's newfound powers.

When they reached at the end of the dungeon, they were met by the one who was watching them. It was none other than Keele himself, turned into a Litch

He meant no harm to them and told them how and why he created that fortress in the first place. Apparently, when Keele was alive, he was a famous heroic mage that defended the kingdom against all its enemies. In some point on his life he seemingly kidnapped a nobleman's daughter. The woman in question was given to the king for political reasons, but the king mistreated her along with the queen and other concubines. He asked for the girl to be granted to him, someone who could appreciate her.

When the king refused, Keele took the woman right then and there. They lived together from one place to other, being chased by the King's army, but he valiantly defeated the troops without killing them. Keele and the woman married in secret. In some point in his life he was mortally wounded while protecting his beloved and forced to forsake his humanity and become a Litch to have enough power to face future threats. With his newfound power he built the dungeon in hopes of discourage any more attempts on their lives. They lived together for many years until the woman  died of natural causes.

Keele began to feel alone without his beloved and asked Cecily to use her new powers as archpriest to purify him so he could be with his beloved again. Cecily, moved by his actions, agreed to purify him and try to reunite him with his long lost love.

With Keele purified, Cecily and Kazuma grabbed the treasure of Keele and walked away from the dungeon safely, not before Cecily leaving a warding off barrier on the dungeon's core, in respect of Keele and his wife.

With the treasure, Kazuma decided to make some dealings with the demihumans of Samuidoh to get fresh butchered vegetables and grain so he could use his "Cooking" skill so he could make some of the most delicious dishes from his original world.

Kazuma copied the Subway's model of business of fresh out-of-the-oven bread and fresh ingredients for the hoagies. Specially the Teriyaki footlong with fresh butchered vegetables.

Kazuma then decided in a bold move to add the Rustic Shogayaki Sub with grated cheese to the menu

It was a little investment but it produced only 120% ROI because Cecily scared some people away offering the Order of Axis pamphlets every time before the clients ordered. Kazuma had to put Cecily on her place by granting her half of the utilities to Cecily for her Axis chantry in Axel in exchange that Cecily didn't get near the restaurant ever again. After that Kazuma's version of Subway called "Kaz's Subs" grew on popularity and the money started flowing again when the Guild's cantina decided to offer Kaz's Subs a branch inside the guild's cafeteria.

Kazuma, at some time on his life thought that thing would've been much easier if he made Aqua going with him to the Fantasy World, but when he saw how Cecily behaved, he knew right then and there that bringing a Goddess as crazy as her followers would've been a very bad idea. After Darkness returned with good news about his retained money, Kazuma's financial future seemed assured, but Kazuma only cared for one thing. Defeating the Devil King and force Aqua into submission for insulting him.