Kiritani Yuu isn't exactly what you'd call a popular guy: he's bored, without a friend, bullied, quite antipathetic, despised by his own sister, and occasionally called "the Invisible Man" for his utter lack of presence. So he's quite unfazed by the arrival of a New Transfer Student, a cute and frail girl named Tsujiura Megumi. That is, until he sees her being harrassed by a group of thugs which she proceeds to wipe the floor with.
Turns out Tsujiura has transfered schools several times after getting constantly involved in fights, and just puts a demure image so that people will leave her alone. The problem is, that image also makes her insanely popular with the boys, which gets on her nerves: she thus asks Yuu, who knows her real nature, to be her "boyfriend" to fend off her numerous suitors. The poor Yuu will have to put up with Tsujiura's alien way of thinking, her passion for Unidentified Mysterious Animals (like the titular Chupacabra) and a lot of pain.
Add to this the gang of Shimon, a heavy metal-themed thug considering Tsujiura his Arch-Enemy, and the former School Idol Tachibana Midori who wants to steal Yuu away from Tsujiura to humiliate her, and you get a leisurely-paced but slightly sociopathic romantic comedy, with an artstyle that may or may not be deliberately awkward. While the story doesn't spare us some clichés, it also likes to play with them, and the deranged characters eventually learn to be more sociable.
Written by Sakurai Atsuhito, Tsujiura-san to Chupacabra (subtitled "Unidentified Mysterious Girl") is a 4 volume series that ran between 2014 and 2015 in the Shounen Champion (which also hosted another insanity-fueled romcom).
Warning: since the series is pretty short, all spoilers are unmarked.
Unidentified Mysterious Tropes in this series
- And This Is for...: While beating up some would-be perverts, she declares each blow in dedication to the fossilized "Mongolian Death Worm" she had just bought and which they had destroyed, prompting the beatdown.
- Bavarian Fire Drill: Yuu uses the (literal) fire drill and a call from the broadcast room to make everyone evacuate and leave Tsujirua alone against Shimon.
- Berserk Button: Telling Tsujiura that UMAs aren't real will set her off no matter how badly she's trying to keep her cool.
- Character Development: What the story is all about in the end. By the last chapter, all the chacters have become better and brighter people, who have learned to cherish their human relationships (though not all to the same degree).
- Cool Big Sis: To Yuu's annoyance, Tsujiura becomes this to Nanako after she saves her from some would-be perverts.
- Fangirl: Yuu's sister Nanako becomes this to Tsujiura after she saves her from her kidnappers.
- Idiot Hair: Yuu has an impressive spike-shaped hair coming out of the top of his head.
- Ineffectual Sympathetic Villain: Shimon and his gang. All of their schemes to defeat Tsujiura backfire spectacularly.
- Jerkass: Pretty much everyone is this to some degree at the start of the story. Especially Tsujiura, who has seemingly never learned that other people had feelings, and Midori whose attempts at bullying her include thumbstacks in the shoes. They thankfully all get better by the end, and that's kind of the point.
- Minimalist Cast: There are only six named characters in total, and only four that are actually focused on. This partly explains the relatively slow pace of the story − not that it moves slowly, but it's not nearly as hectic as these kinds of romcoms usually are.
- No Celebrities Were Harmed: Shimon's design is obviously inspired from Gene Simmons. He's even the Lead Bassist in the band they form in chapter 33.
- No Romantic Resolution: By the end, Yuu realizes that he loves both Tsujiura and Midori, but with no definitive answer as to which he likes more (though the scales seem to tilt heavily towards Tsujiura).
- Non-Indicative Title: The series doesn't feature any chupacabra (except in the very last panel of the last chapter) and it's by no means a central part of the plot. Tsujiura is simply constantly talking about UMAs.
- The Power of Rock: Shimon invoke this constantly. He's apparently so metal you can see his invisible bike.
- School Idol: Midori was this until Tsujiura tranfered in the school and everyone forgot her existence. Overnight.
- Super Gullible: Whenever Unidentified Mysterious Animals are involved, Tsujiura will believe nearly anything, no matter how obviously fake it is to anyone else. A shop owner specializing in such fakes regards her as its best customer because he can take advantage of this.
- Those Two Guys: Shimon's lackeys are apparently here only to comment on their boss' awesomeness or Tsujiura's scariness.