A sub-trope of Anime Hair, this hairstyle resembles the hood scoops on a muscle car and also looks a bit like cat ears, allowing for the visual appeal of the Cat Girl in series that are too "realistic" to actually feature such a supernatural creature. They can also be used to suggest a resemblence to a machine, again, without the work nessesarily featuring something like a Robot Girl. Seems to be more common among females, though male examples are plentiful as well.
The trend started in the late 90s and continued in the early 2000s, most likely popularized by Sakura Kinomoto of Cardcaptor Sakura.
Seems to be especially prevalent in Visual Novels.
- Miyabi Hotaka from Absolute Duo has this hairstyle.
- Shironeko from Akazukin Chacha, being a nonstandard take on a Cat Girl, has these instead of cat ears.
- Isuzu Sento from Amagi Brilliant Park has these, along with a Hair Antennae.
- Kaede Kayano a.k.a. Akari Yukimura from Assassination Classroom sports these. They serve to hide her own tentacles.
- Sakura of Cardcaptor Sakura and Tsubasa -RESERVoir CHRoNiCLE- also sports this hairstyle, combined with a Hair Antennae.
- Fear from Cube×Cursed×Curious has this hairstyle.
- Mutsuki Ichimonji from Happy Lesson has these.
- Koneko from High School Dx D has them, adding to her Cat Girl motif. She actually is a Nekomata, and sprouts actual cat ears in their place when using her full strength.
- Seara August from I Couldn't Become a Hero, So I Reluctantly Decided to Get a Job has them.
- Akari from Jewelpet Twinkle has this hairstyle.
- Yukari in K has this.
- The titular character of Karin has such large intakes that they make up more than half of her total hair, a rarity.
- Mermaid Melody Pichi Pichi Pitch: Lucia has these, combined with an Idiot Hair.
- Ms. Smith from Monster Musume has these (more noticeable in the manga).
- Haru from Ojojojo has small ones resembling horns. Her and Tsurezure's child in the epilogue inherited them.
- Omamori Himari's Token Mini-Moe, Shizuku, has this hairstyle in its most magnificent form.
- Ada from PandoraHearts sports this hairstyle.
- Tsukiumi from Sekirei has this hairstyle.
- In Sunday Without God, Ai and her mother Alfa have this hairstyle. In Ai's case, she also has a Hair Antennae.
- Aoi of Six Gravity (Tsukiuta) has them. Apparently, they're supposed to resemble wings.
- Violet of Violet Evergarden has this hairstyle, both during her Child Soldier and post-war typewriter outfit.
- Kyou and Ryou Fujibayashi of CLANNAD both have these quite prominently. Kotomi Ichinose has a less impressive set.
- Da Capo II has Yume and Otome Asakura.
- D.C.S.S.: Da Capo Second Season features Nanako Saitama.
- Continuing with the Key/Visual Arts theme, Kanon has three such characters, Kaori Misaka and Nayuki and Akiko Minase.
- Featured prominently in Muv-Luv. Sumika Kagami has these, as well as Marimo and Meiya. Miki "Tama" Tamase has typical hair intakes along a rare hairstyle that includes even larger cat ears.
- Meiya's in particular are so massive her hair design was apparently inspired by the Gundam GP02.
- To Heart 2's Tamaki Kousaka has these.
- Arcueid Brunestud from Tsukihime has a rather impressive pair of intakes in the original release. Her design for the remake apparently reduces them to just one, which is almost vestigial.
- Aoko Aozaki from Mahou Tsukai no Yoru and her earlier appearance in Tsukihime.
- Monika, Yuri, and Natsuki from Doki Doki Literature Club! all have this. That's three quarters of the cast.
- Senna has them in the August 18, 2012 strip (#11) of Sandra on the Rocks (just NSFW enough to not be linked).
- Parodied in this tumblr post, which claims that an anime girl's "hair vents" are a vital organ for facilitating gas exchange to control body temperature, and without them they will overheat and die.