Mahiro and the Guidance of the Stars

Mahiro and the Guidance of the Stars (まひろのサプライズパーティー, Mahiro no Sapuraizupātī) is Chapter 35 of Onimai: I'm Now Your Sister!. It was originally published on Pixiv on December 28, 2019.

Summary
Mahiro and her friends get in on the new horoscope craze.

Plot
Several girls in Class 1-B are reading horoscopes. Minori complains about getting a bad one. Mai reads hers and says that her lucky color is red, to which Miyako offers her a red pen to borrow. Mahiro watches all this and thinks to herself how horoscopes are suddenly the "in" thing, and how girls seem to love this stuff. Nodoka reads Nemu's horoscope, based on the fact that Nemu is a Sagittarius, and reads that people who are a Sagittarius need to be careful about oversleeping, as they might lose something important. This causes Nemu to immediately sit up awake, and Mahiro laughs, thinking how horoscopes have incredible power over these girls.

Later at home, Mahiro sits on the couch and reads a magazine. Mihari asks her what she is reading, and Mahiro shows her that she is reading a horoscope magazine called Fortune Telling Guidebook. Mihari is a bit surprised, then uses the opportunity to make fun of Mahiro by pointing out how girls are really into this stuff. Mahiro is shcoked and insists that she's only doing it because everyone else in class is into it and she wants to know what they are talking about. Mihari just giggles and replies "whatever you say", to which Mahiro gets angry and points out that Mihari doesn't even know what it's like for her.

Mahiro then gets the idea to look up Mihari's horoscope, remembering that her birthday is in April. Mihari says that there is no need for that as she doesn't believe in horoscopes anyway. Mahiro call her boring for saying that. Mihari points out that the stuff is written so it could basically apply to anyone, calling this the barium effect. She further explains that it'll say meaningless stuff, giving examples as "You'll have stress in your life" or "You have a serious side". She suggest that Mahiro test it out by checking a different sign's horoscope as well, betting that it'll all still be just as "accurate" for her. Mahiro sighs and notes that this is why it is so hard to relate to her.

Calling her "Dr. Oyama", Mahiro looks up Mihari's horoscope. It says that for those born in April "Try not to get hung up on logic and insist on being right all the time! You might be raining on someone's parade!". Mahiro points out that is spot on for Mihari, which causes Mihari to feel embarrassed.

To get back at her, Mihari decides to read Mahiro's horoscope. It reads "Beware of overlooking important dates! You might be suprised with luck in your future!". Mahiro is confused by the mention of important dates, thinking that are aren't any major holidays coming soon. Mihari is shocked and begins to tell Mahiro what the important date is, but relents at the last minute and chuckles, telling her to forget it. Mahiro is left confused by this.

The next day, Momiji wears an eyepatch to school and Mahiro notices that she also has a dark smile. Mahiro tells her that she's getting worse, but Momiji points out that eyepatches are today's lucky item. Mahiro points out to her that wearing an eyepatch is dangerous and that she could get hurt.

Miyo has started using tarot cards and holds up the card of death while reading Asahi's fortune with them. She remarks to Asahi that the death card in the upright position means that Asahi is going to die. Asahi is freaked out, while Mahiro notes to herself that this doesn't look right either.

Mahiro thinks to herself that this whole thing is getting out of hand, but supposes that all of them are at that age where this stuff is fun to them. After Miyo suggests that she should take up black magic, Mahiro notes that this has gone far enough and asks them if there are less dark ways to do this. Miyo asks for suggestions, and Mahiro thinks back to what the book said. Mahiro comes up with the idea of spirit animals, saying that it's a way to divine which animal drives your personality. Momiji notes that it sounds fun. Mahiro realizes that she has no idea how to actually do this, so she decides to just make it all up as she goes.

Mahiro decides that since Asahi is so energetic and friendly, her spirit animal must be the dog. Momiji notes that that is perfect for Asahi.

She decides that Miyo's cuteness must mean that she's the rabbit, also thinking that it's also because she's horny 24/7. Miyo ends up blushing from hearing that compliment.

Mahiro thinks that Momiji might be the kokeshi, but backpedals and decides that she might be the bear, since she's soft-hearted and reliable. Asahi also adds on that Momiji is also ferocious, which fits into that as well. Momiji hits Asahi on the head for saying that.

Miyo asks Mahiro which animal she is, and Mahiro decides to take a crack at it. She says that with a heart overflowing with kindness, she must be "the mighty elephant". This throws the three girls for a loop, as they imagined Mahiro as being the koala. Not only due to what she said above, but also supposedly due to her cuteness and laziness. Mahiro asks them if something is wrong, to which Momiji says that nothing is wrong.

Momiji gets the idea to do a regular sun reading, and Mahiro agrees. Momiji asks Mahiro when her birthday is, and then thinks to herself how this is a trap. She's only offering to read Mahiro's horoscope as a ploy to find out her birthday. She thinks how once Mahiro has forgotten all about it, she'll surprise her, calling it the perfect plan. Mahiro says that her birthday is in March, then remembers that her birthday is actually today, having forgotten all about it. Momiji's mission fails, but all three are happy and wish Mahiro a happy birthday.

When Mahiro gets home, Mihari appears with a birthday hat and wishes Mahiro a happy brithday, guessing that she completely forgot. She says that the firtune telling book gave her the idea to surprise her. Mahiro fakes being surprised, but Mihari sees through it and says that she doesn't need to pretend. Mahiro admits that she actually remembered earlier today, which causes Mihari to laugh and say that she guesses that it's not much of a surprise then.

Mihari presents a birthday cake to Mahiro. Mahiro says that she has mixed feeling about this, as it is a little weird getting older when she looks the way she does now. Mihari asks how many candles she should put on, and Mahiro admits that that really is the question to ask.

It is revealed the Kaede saw Momiji wearing the eyepatch at home.

Characters

 * Mahiro Oyama
 * Mihari Oyama
 * Kaede Hozuki
 * Momiji Hozuki
 * Asahi Ōka
 * Miyo Murosaki
 * Aoi
 * Miyako
 * Minori
 * Mai
 * Nemu Fujimi
 * Nodoka

Trivia

 * This episode takes place on March 6, as Mahiro's birthday is March 6.
 * Nemu is revealed to be a Sagittarius, which would place her birthday anywhere between November 22 and December 21.