When an orphaned god from the adjacent prefecture breaks through the boundary into Tamagi to reclaim his father's lost powers, Mizuho volunteers to help him.
Boundaries in January contains the following examples:
- Bait-and-Switch: The order of who threw out what during the rock-paper-scissors match.
- A Day in the Limelight: For Mizuho.
- Entertainingly Wrong: Played for Drama. As Madoi originally arrived in Tamagi to reclaim his father's power, Mizuho believes it is still his priority and goes out to find it when he begins to weaken. Near the end, she is shocked to realize that Madoi have given up wanting his godly powers, and instead wanted to spend his last moments with his new big sister, Mizuho.
- Furo Scene: A heartwarming one with Mizuho and Madoi.
- Heroic BSoD: Mizuho after being forced apart from Madoi.
- Home Field Advantage: The primary thing that allowed Shiro's Victory by Endurance.
- Innocent Innuendo: Both Mizuho and Kouhei think Madoi's request to "wash his front" meant something other than rinsing some leftover shampoo out of the front of his hair when he and Mizuho are taking a bath together.
- Loophole Abuse: The resolution to the January story. Mizuho cannot cross from Tagami to Sagashima to see Madoi, so Masaki takes her into Sagashima via a third prefecture.
- Luck-Based Mission: Mizuho realizes this is the only way she has a chance of beating Shiro.
- My God, What Have I Done?: Mizuho has one near the end when she realizes she was doing what she thought was best for Madoi but not actually what he wanted.
- Overused Running Gag: Grandpa Tagami thinks Mizuho's constantly thanking him for his help at the end of the story is turning into this.
- Poor, Predictable Rock: Used during the chapter's rock-paper-scissors match.
- Together in Death: Madoi's parents.
- Victory by Endurance: How Shiro killed Madoi's father. Since he was slowly being poisoned by being outside of his boundaries, Shiro just kept him chasing her until he was weak enough to finish off.