As you should very damn well know at this point, one of the biggest things about Imu is her huge love and affection towards Miyabi, her childhood friend. It's very similar to Yagyu's love and devotion to Hibari (hold this thought for later).
Imu's personal story focuses on her trying to get Miyabi to notice her more and win more of her heart over, such as dressing up, practicing poses, and making her voice sexier. But she doesn't just do this by herself. She also wants to search for other girls that can help her win Miyabi's heart over her.
Of course, since you've already likely seen the thumbnail of this video, you could also consider this a "How I Got There" story for Imu.
----------
In Mission 2-01: Operation: Wiles, Imu finds Yumi for a fight and is pleased with her graceful, dance-like moves during battle. She tried to imitate Yumi's traditional Japanese dancing, and got pissed at Yumi when she giggled at her attempt. Imu really wants to win Miyabi's heart with this. They could possibly dance together if she can learn to dance, herself.
In Mission 2-02: Attractive?, Imu continued practicing the dances she learned from Yumi. Katsuragi saw this as a mating call, or rather, a groping call. She suggested that Imu should squeeze her own breasts more to win Miyabi over, and tried to teach her ways to grope. She even allowed Imu to grope her as an example. Ultimately, Kat just wants to grope Imu, period, but Imu fled.
In Mission 2-03: Cute?, Imu nonetheless followed Katsuragi's advice and starts fondling herself to boost her morale for Miyabi. Hibari got weirded out by this, but then Imu got absolutely stunned by Hibari's adorable face. Hibari says that being cute makes her stronger and vice-versa. This made Imu believe that if she were to beat Hibari, then she could get cuter AND stronger for Miyabi, too.
In Mission 2-04: Girly?, Imu finds Shiki, who quickly tried to give her face a massage. She wanted her to be less stiff in the face and try to do more silly and girly things. Shiki suggested having Imu do a funny face, and when she did, Shiki takes a picture of it with her phone. Imu then beats the pic out of her.
Lastly, in Mission 2-05: For Our Happiness, while Imu imagined what would've happened with Miyabi if Shiki was able to keep her snapshot of Imu doing a funny face, Yagyu tracked Imu down, being angry at her for the beating she gave Hibari before. During their fight, the two girls realized something they have in common: They both fight for their own loved ones. Imu fights for Miyabi, while Yagyu fights for Hibari (that's why I said "hold this thought" before). They likely would've gotten along with each other had they not have to fight like this.
----------
In the end, Imu defeats Yagyu in their fight, and as a part of that deal, Yagyu now had to accept Imu's wish of making her cuter. Yagyu unleashed a special Secret Ninja Art known as Cutelfish on Imu. The art completely changed her clothes, but ensured that Imu had become much MUCH cuter than she ever was before.
Imu then returnd to Hebijo and checked out her new cuter look in a reflection... She now has pink hair... and blue ribbons... and a pink jersey... and... dark blue gym bloomers?
It then became very clear from there. Yagyu's Cutelfish art was just her dressing Imu up as Hibari! Imu felt so embarrassed by this, and planned to take off all of the clothes that she didn't think were cute on her.
But then... as if it were fate, Miyabi walked in on Imu, and gazed upon her new Hibari-inspired look. She was actually quite infatuated with it. Miyabi could not contain her feelings over how adorable Imu looked now. She simply HAD to pick her up and hold her in her arms.
Imu's plan was successful, and she was in pure bliss over having Miyabi open her heart back to her. Imu was so aroused in this moment, that she started bleeding out of her nose.
If it means that Miyabi can keep showing her own affections towards her, Imu plans to keep a part of her new Hibari look every day, now. This would be the key to their true love...