Tanya's new battalion is off the ground and running, and it's time for them to do their first mission: fight back a massive invasion by the Dakian Dukedom to the southeast. The enemy army numbers in the hundreds of thousands, but they've brought no air units at all, which makes them easy pickings for Tanya's highly trained force. After wiping out the enemy army, she heads straight for the enemy capital and launches an attack there.

Tanya is now living life on easy street, as a highly-respected student at the military university. She's so highly respected, in fact, that one of the Empire's chief military planners asks her for her opinion on the course of the war. Eager to show off her intellect (and hopefully land herself a cushy job in the planning department), Tanya comes up with a plan of astonishing insight and intelligence. Her idea backfires, however, when she turns out to be a little too smart for her own good...

After her stunning success with her first mission, Tanya is assigned to test a new piece of technology: a highly unstable prototype calculation jewel. This jewel offers her unparalleled power, but just using it risks her life. Tanya is determined to get out of this project and on to someplace easier and safer (like the front lines of the war), but Being X has other ideas...

The secret of Tanya's birth is revealed. Tanya was a cold and unemotional Japanese salaryman who was pushed in front of a train by a man he laid off. An infuriated godlike creature named "Being X" sent him to this world, and reincarnated him as a baby girl... with no promise that he would ever be reincarnated again. Now Tanya has to survive, because this is all she's got!

Tanya just barely manages to restrain herself from disobeying her superior officers and attacking the Republic remanents. But the Republic forces have escaped overseas, and vowed to fight to the bitter end. The Empire has been victorious, but in its victory it has terrified the rest of the world and spurred them to action. Is true victory possible at all?

Tanya's diminished smaller company attack the battalion of Allied Kingdom mages rather than retreat. Their company use their altitude advantage but suffer heavy losses, especially when Colonel Sioux uses an illegal Trench Gun.

Tanya's spectacular mission is a success, and the Republic is surrounded and crippled. But on her way back, she runs into a group of allied mages, lead by Anton Souix, the man she crippled once more. He's back, and powered by Being X, and his one mission in life is to take down the Devil of the Rhine!

The Empire is a powerful military nation on a continent that looks much like early 20th century Europe. But in this world, magic is real. The Empire is involved in a war against the Entente Alliance, and fighting a poorly executed delaying action in the northern theater. Second Lieutenant Tanya Degurechaff leads a small platoon of mages. But there's something unusual about this lieutenant... she's only nine years aold!

It's Kanna's sports festival. However, when she learns Miss Kobayashi is too busy at work to come, she sulks. Miss Kobayashi wonders why she'd want her to come so badly when she isn't Kanna's parent, but Kanna already views her as one. Even Takiya tells her, "You should decide based on if you want to go, not if you can go." Finally, the day of the sports festival arrives. As a dragon, Kanna should have overwhelming physical prowess, but...?!

Kanna asks Miss Kobayashi to make her a lunch box for her field trip. After Tohru says to leave it to her, the two break out into a match to see who's better at it! Lucoa and Fafnir are added to the judge's panel, presiding over the cooking competition between Tohru and Miss Kobayashi! And finally, a brand new dragon girl appears! Arriving with the sudden destruction of Miss Kobayashi's home is Elma, who's on terrible terms with Tohru. Elma values and order and fears Tohru may disrupt relations with humans, so she challenges her to try and take her back by force!

Miss Kobayashi and the others go to the beach. But Lucoa's immediately dragged off by one of the lifeguards for her overly skimpy swimsuit. After regrouping, they put sunscreen on each other, split a watermelon, go swimming together, and enjoy summer to the fullest. After the beach, it's comiket! Tohru and Miss Kobayashi both head for the otaku's battlefield, and even Tohru gets shivers from the incredible aura surrounding those otaku. While helping Takiya with his circle, Tohru's horns and wings are mistaken as cosplay?!

Kanna is invited to Saikawa's home. Since Saikawa's family has a maid too, they invite Miss Kobayashi and Tohru to join her. When a genuine maid, Josie, greets them, Miss Kobayashi gets excited. The two hit it off, chatting about maids. To top things off, Lucoa announces she's planning to live in this world too. She claims she was summoned by Shouta, a member of a mage family. Lucoa gets very touchy to try and get along with Shouta, but she goes overboard...

Tohru's finally gotten the hang of her maid duties. Suddenly interested in what Miss Kobayashi does at work, she heads out to observe. There she watches how everyone relies on Miss Kobayashi and falls for her again. However, there's also a boss being mean to Miss Kobayashi, which makes Tohru very angry... Out on the town she runs into Fafnir from the other world. Since he says he'll be living in this world too, Tohru winds up helping him find a place to live?!

Kanna watched the elementary schoolers going to school with jealousy, so Miss Kobayashi decides to let Kanna attend elementary school. Miss Kobayashi, Tohru, and Kanna all set out to the shopping district in order to buy Kanna's school supplies, but Miss Kobayashi is overwhelmed by the modern stationery store recently built. On the other hand, both Tohru and Kanna are intrigued by their first sight of stationery stores. After they finally gather all the supplies she needs, it's time for Kanna to join the school!!

Kanna starts living with Tohru and Miss Kobayashi. While the livelier residence is nice, sharing a tiny apartment with three people becomes cramped. So Miss Kobayashi decides to move. She winds up inviting Takiya to her new apartment for a party, but Tohru also invites her dragon friends, Fafnir, who lives in a cave, and Lucoa, who's lived in this world since ancient times, to visit their new home.

Miss Kobayashi was growing accustomed to her new life with Tohru, and so they headed out to go shopping together. She's surprised by Tohru's social skills though, when she sees how friendly Tohru was with the people of the shopping district. However, Tohru herself makes the dark claim that she's only pretending to be friendly, and shows how she still doesn't understand human emotions. Then on one of her days off, someone calls at Miss Kobayashi's home. She opens the door to find a little girl with horns and a tail--?!

Their day off is peaceful, and Miss Kobayashi spends her time relaxing with the others as usual. However, while out shopping, Tohru suddenly stops to think on the street--Miss Kobayashi is human, and what will she do when her lifespan runs out and she dies...? They can't be together forever. They'll have to part someday. She knew that. She was prepared for that. Yet still, Tohru's mind is in turmoil, and the final blow is dealt when the Emperor of Demise--her father--appears before her.

Tohru's now capable of handling the housework perfectly, and at Miss Kobayashi's request, she decides to make the best omurice for dinner one night. However, gathering high quality ingredients would put her over budget. Wanting to see Miss Kobayashi smile more than anything, Tohru ends up playing her forbidden card... Meanwhile, as Miss Kobayashi rides the train home, worn out from work, she dreams of the night she first met Tohru.

The end of the year is drawing close as well. When Tohru plays the lottery at the shopping district, she wins a prize--a kotatsu, not the hot springs trip. Once they finally join Miss Kobayashi in the kotatsu, the dragons start lazing around... The kotatsu ruins not only humans, but dragons too. That relaxed, lazy mood is how Miss Kobayashi's family ends up spending their end of the year and the new year. Their peaceful days off pass by uneventfully. Meanwhile, Tohru and Kanna also change into kimono for their first shrine visit of the year--?!