Ryuuji trying to make sense of getting dumped by Tomoko and his jealousy for Junta.
In the second episode, Tomoko has invited Junta to a bar, and tries to apologize to him for how she led him on earlier. He goes into Mega Playboy mode, they are about to kiss... Then we're treated to Tomoko's recently dumped boyfriend Ryuuji flattening his face on the window in his jealousy, the owner interrupts the moment because every girl in the bar has started lusting after Junta, Junta returns normal and sees Tomoko's cleavage, and his allergy to women kicks in.
Ryuuji's thugs shouldn't be here... But imagine three random Fist of the North StarMooks in a bar for couples, add the fact one of them has pointy ears, and try not to laugh.
After the thugs above have fallen to Mega Playboy!Junta going Super Saiyan on their asses, Karin comes down ready to deal with the Mega Playboy, having to get rid of him at all costs. Then she looks at his face up close, and falls for him. The only reason she didn't jump him then and there was that she had not slept for days, and the sight of the Mega Playboy broke through the nervousness that had kept her awake until then...
After Ami does see Karin and gets the wrong impression, Junta's mom Chiyo shows up. And we finally find out why Karin is wearing only a bra and a pair of panties: Chiyo replaced her suit with the lingerie in her sleep because she was sorry to have her sleep in that "rain cape-thing".
After the above, Karin apologizes for suspecting him of undressing her, and he tries to smooth-talk the cute girl. Emphasis on try. Especially as Karin has decided it will be good for the rest of the world that Junta hooks up with Ami, and in the attempt to convince him she drops the sheet she was using to cover herself...
The first time Junta goes Mega Playboy on Ami. The one girl immune to the Mega Playboy's charm.
Tomoko calling Normal!Junta a playboy. Right after he snapped out of Mega Playboy mode. She then ropes him into going shopping with her.
The corollary to all of this: the day after, on the school's rooftop, Karin gives Junta a piece of his mind, Junta replies she looks jealous, then moves closer, very close, his face nearly touching Karin... And then he steals the receivers of her tracers and tells her he knew she had just put one on him during the pilerdriver. We later see her in her time machine gloating she has tons of spare receivers while spying on him with a flying camera.
Karin: "I want you to check if I caused a history-changing problem when I injected Momonari Junta with that DNA Control Medicine."
Oharu *sounding bored*: "All set with that check... Probability that the DCM has caused Momonari Junta to become the Mega Playboy is... 120 PERCENT!"
After receiving the right DCM bullet, Karin decides to get Junta on the school's roof and snipe him from away. She cocks the hammer, takes aim, tries and convinces herself she has to shoot, both for her dream and to avoid execution, finally pulls the trigger... And fails to fire because she has subconsciously put her thumb between the hammer and the firing chamber.
In episode 10, Ryuuji's newfound ability to shape-shift provides some fun:
First, we have Ryuuji and Tomoko dealing with the discovery of the ability, that happened when Ryuuji transformed into Tomoko in a bathroom: Ryuuji, after desperating for a moment because he would never be able to kiss Tomoko anymore, decided to grope himself-as-Tomoko to feel her body, only to later see that only his face has transformed (thus he had groped his own manly ass); immediately after that, Tomoko barged in, saw Ryuuji with open shirt, pants and boxers down, and her face, blushed, calmly came out, closed the door, and then screamed "AAAAAAAAAAAAAAAAHHHHHHHHHHHHHH! I'M IN THERE!". Thankfully, by the time Ami and the school's nurse (called because Ryuuji had been shot, after all) came in Ryuuji was back to normal...;
When Ryuuji is molesting Ami while wearing Junta's face, he touches her leg... And then suddenly absorbs her DNA and transforms completely into her, not just the face but the whole body, boobs included.