In Sapphire's introduction scene, she's blasting monsters...and lamenting that she's sending fellow students to the darkness. Then Almaz, in Save the Princess mode, rushes up to her...and gets blasted too. Sapphire and Mao then hit it off when the princess admits to being a 'killing machine', much to Almaz's horror.
Raspberyl and Co.'s Big Damn Heroes moment is sidetracked by a stunning revelation from Mr. Champloo- they're graduating! What follows is an utterly hilarious and played-completely-serious graduation ceremony, while the final boss of the level sits on the sidelines and waits.
Prinny #1: We were invited to volunteer work...
Prinny #2:...and were verrrry annoyed.
Nearly any scene with Champloo. While we see there's some Hidden Depths to him, his dialogue, especially the early stuff, is still hilariously insane, especially since Mao and Almaz actually agree that they can't make any sense out of it.
Sapphire, at one point, decides to take action to open Mao's heart. With a chainsaw. Mao and Almaz have the predictable reaction, and Sapphire says that she heard demons can't die from things like this, to which Mao says is a lie and runs away. Sapphire chases after him and says that maybe a chainsaw was too painful she'll use a surgeon's scaple instead.
Almaz finding out Mao's father in the second encounter has a plug and being plugged into a wall socket.
Upon achieving "Mao's ambition" ending, you get this at the end:
Mao: Now that's come to this... The only option left is, to reset.
Mao's reaction towards learning Baal was the thief:
Mao: Tyrant Overlord Baal!? Wasn't he just a ploy to force players into playing their games for 1000 hours longer!?
One of the things you can steal while having a thief's evilty is "Balls".
Black Eyes Blue Prinny's description: Sacrifice 3 gods to summon a normal Prinny. Can't attack with White Lightning.
Likewise, everything involving with Se-to-oh.
In The Vita Updated Release, in final map of Master Big Star and Salvotore's scenario, We get this dialogue during the cutscene:
Prinny Clicks the "bomb remote".
Prinny: Oh, crap! I accidentally brought my TV remote! Dooooood!!!
Master Big Star admitting he done the same mistake also, and Mao lampshading on the failed attempt.
The many different ways Mao has to open his heart are rather bizarre and actually kind of funny, especially when even Raspberyl and her crew wouldn't go that far in doing an act of kindness.
First, he tries to eat a sunny side egg with hot sauce or something similar to that effect, but the Mao in his heart calls them out on being rather dumb in actually believing that will work. Before that, they also make a big deal out of saying eggs aren't supposed to be eaten with salt and pepper, which you have to fight a bunch of Maos that have a big Berserk Button about it.
The second time seems to work, but it's rather weird... one of the ways to do it is having Mao actually attend school, which not going to school is actually considered a GOOD thing which is rather redundant. As his rival, Raspberyl tries to do the opposite and actually get graduated. It involved something like dance moves, and Raspberyl is actually there too telling him "Good job!" This one on the other hand actually seems to have worked.