Gotta flirt to save the world!!High schooler Takuma Akutsu is terrified of human contact and just wants to live a quite life. Too bad he doesn't have a choice in the matter when nine Valkyrie sisters come barging into his home! They've tasked him with raising their level to fight off the monsters threatening humanity--and how will he do that, exactly...? By gettin' down & dirty to the max!!!

Date or die!! Get naughty or humanity is done for! It's Mutsumi's turn to step into the spotlight! The soft-spoken Valkyrie finally gets to go on a date with Takuma, but idols are under a strict love ban--no dating allowed! That means they're gonna have to go incognito if they want to gain enough experience points to level her up. Will they be able to stay under the radar, or are both Mutsumi's idol career AND the world doomed...?

While carrying out the ultimate Val Love with all the Valkyries, Takuma Akutsu thought deeply about who the partner he loved the most, who his heart’s desire, truly was. Now, Takuma shares a soul with the one who came to his mind, and they swear to live together as two!

The valkyries, defenseless without lovers, come under attack by demons! Their only salvation lies in Takuma, Nanaki, and a level of perversion unlike anything the world has ever seen!

Do perverted things to nurture my power! While Takuma has done a good job raising some of the Valkyries' levels, there are a few he still needs to give some tender loving care. Enter Misa, rowdy older-sister type, and Yakumo, frigid ice queen. Every experience point counts as they prepare for the war ahead...Can Takuma romance these hard-to-get maidens?

And that’s how I became a harem protagonist! Takuma has come a long way as a hero and lover, but just how did he get involved with the nine valkyrie sisters? Discover the oh-so-revealing origins of Natsuki’s first voyage to Japan from Asgard, and her passionate first lovers’ contract with Takuma! The future is just as important as the past, though- an unexpected visitor has arrived to tell the truth of why the valkyries were sent to Earth!

The mysterious maiden… …fully disrobed! Just when Mutsumi found an ally in her quest to support her family through wealth and fame, it turns out Niina’s…sleeping with the enemy?! And when Yggdrasil goes berserk in the middle of the city, it’s time for Takuma and Shino to take their relationship to the next level…But is their love strong enough to stop the rampage?

Little Kururi-chan’s all grown up!! After little Kururi put on a magic helmet, she grew in all the right ways—except one. Her sweet, adorable kid-sister charm is gone—and what remains is a rebellious teenager with no interest in boys. Now, if Takuma wants to catch Kururi’s attention, he’ll have to pull out all the stops to help Kururi gain enough experience points to level up. But how does someone as shy as Takuma sweep a teenage girl off her feet…?!

HATE ME, KILL ME, SPITE ME PLEASE! The valkyries and Takuma head to the depths of Niflheim to save Yggdrasil! But the path there is crawling with formidable enemies, and they need a continuous supply of aether to make it through. In this current crisis, that leaves just one option to replenish power: having lots and lots (and lots) of hands-on fun. And as Gerhilde makes moves of her own, what truths about her and Loki will be revealed?

Chaos reaches its peak as a traitor has appeared among the ranks of Asgard. As trust between comrades breaks, how will the ensuing battle turn out? The path to salvation isn’t easy, but hope remains for Takuma, the valkyrie sisters, and the entire world. It’ll take some unorthodox tactics, though—including having some fun in the tub and plotting with both frenemies and catgirls!

I want to protect everyone, which is why I'll kill them all. Yggdrasil is on the verge of collapse, and a demonpossessed Futaba is preventing the valkyries from reaching the world tree. All hope seems lost, but Takuma has a plan to mitigate Futaba’s firepower and save Yggdrasil… and it involves everyone taking off all their clothes! They’re not the only ones discovering new powers, though— Skuld’s lover, Niina, has a revelation of her own!

Wicked gods have lovers too! Ichika and Takuma’s date gets interrupted by none other than Loki! When this devilish goddess offers to spice up their date, will Takuma refuse…or fall prey to her alluring figure? Meanwhile, Mutsumi seeks advice from Niina about how to make Takuma happy-in bed. At the same time, Niina struggles to connect with Skuld on an emotional level… Then, on Valentine’s Day, the nine valkyrie sisters have a special surprise lined up for their boy Takuma!!