As introverted colleagues at a travel agency in Tokyo, Takuya Oohara and Rika Honjouji both cherish their happily single lives. After work, home is where they feel most at ease: Takuya unwinds with his cat, while Rika studies various maps. However, an uncertain future looms over their treasured tranquility when their company plans to open a branch office in Alaska within one year and transfer an unmarried employee there. During a day off, Takuya and Rika accidentally meet and, despite never having spoken before, open up to each other about their relocation fears. Feeling encouraged by Takuya facing the same predicament, Rika suddenly proposes a daring solution—to pretend to be engaged for 365 days. Takuya accepts, but little do the two know that the path to marriage may, in many ways, change forever the very lifestyles they struggle to preserve.

Reeling from her recent breakup, Momo Ayase, a popular high schooler, shows kindness to her socially awkward schoolmate, Ken Takakura, by standing up to his bullies. Ken misunderstands her intentions, believing he has made a new friend who shares his obsession with aliens and UFOs. However, Momo's own eccentric occult beliefs lie in the supernatural realm; she thinks aliens do not exist. A rivalry quickly brews as each becomes determined to prove the other wrong. Despite their initial clash over their opposing beliefs, Momo and Ken form an unexpected but intimate friendship, a bond forged in a series of supernatural battles and bizarre encounters with urban legends and paranormal entities. As both develop unique superhuman abilities, they learn to supplement each other's weaknesses, leading them to wonder if their newfound partnership may be about more than just survival.

Grief-stricken over the death of his last family member, his dog Hanako, picture book writer Hotaru Yuuyami suffers from writer's block for nearly two months. Despite his childhood friend and editor Tsubaki Uehara's best efforts, nothing seems to alleviate his pain. But all of this changes one day with the sudden apparition of Kinoko Inu, a mysterious mushroom from his garden that turns into a dog-shaped animal. Much to the great dismay of Tsubaki, Hotaru hastily invites the creature into his abode. Days after Hotaru and Kinoko Inu start living together, the strange mushroom-dog decides to burn the last of Hanako's personal belongings in order to alleviate Hotaru's depression. However, the cohabitation between the overworked writer and his mischievous guest proves more difficult than expected, and Hotaru must let go of his grief if he wants to properly take care of Kinoko Inu.

For blasé college dropout Tsunehiro Sasaki, life has become hopeless. After failing to enter a top university, he has lost all his money trading on financial markets and is now critically indebted. To add to his misery, he learns that he only has at most two years left to live due to an incurable disease. The trajectory of Tsunehiro's life suddenly changes after a group of amateur fishermen saves him from drowning as he was trying to escape from a trio of creditors. While Takaaki Tsutsujimori pushes Tsunehiro to work at the group's workplace—a convenience store that doubles as a fishing shop—Hana Ayukawa tries to share her love for fishing. Although the attempts of the joyful group of anglers initially prove unsuccessful, Takaaki urges Tsunehiro to take a fresh start in life, and the young man eventually accepts the fishing enthusiast's assistance to pay off his debts. As work, friendships, and an unfamiliar hobby all suddenly find their way into his life, Tsunehiro must find the strength to change his ways if he wants to make the best of his remaining time.