The fact that Yu is on a New Game+ run is hilariously lampshaded by the opening and everything he does.
Giving Morooka a handshake◊ after the latter tries smacking him.
Yu looking at Marie while she's reciting a poem. Even the music stops just to sell it.
Yu's nonchalant reaction to everything weird happening around him, really. Like talking to Teddie as soon as they meet and singing the Junes's theme song with Nanako. Hell, the first episode is basically how fun and awesome New Game Plus is.
One of the eye catches has a topless Yu staring at Nanako while wearing a goofy pair of glasses.
Episode Two: "The Perfect Plan"
Having heard that Yu just got his motorcycle license, Adachi drives Dojima's scooter to the gas station to give it to them. Dojima nonchalantly punches him off it.
Yu desperately hitting on everyone he can to win his bet with Yosuke including a grandmother, a woman who claims her eye is possessed, and a cat.
When Yu asked Chie, Yukiko, and Rise if they're free on Christmas, they assumed he was asking them out on a date. Naoto's response? She assumed he was using the date as a cover for him to murder her. And thanks to her detective skills, it all escalates to her thinking all the girls are trying to kill her. Naoto, the person who can be considered to be the Investigation Team's Only Sane Man, believes that the close friends who she bonded and fought alongside with for several months are planning to kill her.
Come Christmas Eve, she comes over decked in body armor, an anti-riot helmet with a collapsible baton.
And of course, she has to reach the house once everyone is "dead" and covered in "blood" (tomato juice)
And then Yu comes back at that exact moment carrying a kitchen knife...
Chie was considering watching a Christmas movie for her date. Her movie of choice? Something about a Bruce Lee Clone battling Santa.
On Christmas, the girls still haven't forgiven Yu yet and are secretly kicking him underneath the table.
Episode Nine: "A missing piece"
The episode begins with Igor welcoming Yu to the Velvet Room... and with Margaret too focused on trying to think up a poem to notice Yu. Cue Letting the Air Out of the Band with Igor staring at Margaret.
While the boys are taking a bath, Yosuke brought up the last time they went to the hot spring at Yukiko's inn. Cue a flashback of the girls throwing buckets at them and the boys put their heads down in disappointment.
Episode Ten: "Not a friend anymore"
Yu and Marie calling each other "moron" while the investigation team just stares at them. Teddie's face in particular is priceless.
Episode Eleven: "Let it OUT! Let it GO!"
After being told by Rise that Marie was hugging Yu too long, Marie responds with a deadpan delivery of one of Rise's lines. Rise is less than amused.
Rise: That's mine, all right? If you're gonna steal it, then you need permission from my agency!
Instead of "Guys versus the Girls", EVERYONE circle around Yosuke and pelt him with snowballs. Especially Marie who throws multiple snowballs like a Gatling gun (Epic that she uses her powers to make it float).
It seems that Yu ALSO wanted to see the girl's bathhouse by stacking multiple buckets as leverage. He thought he was safe until Marie noticed him and cast Ziodyne onto the boys.
That or he knew thanks to New Game+ the wall was going to come down and built the wall to remain out of sight and avoid punishment. Sadly he didn't reckon on Marie.