Strawberry milk helps you grow, tantei-kun

When in doubt, do a flashback

Gintoki had hoped that the new kid syndrome would make the whole school affair a bit easier. He was gravely mistaken. 

He now sat at an empty table to eat lunch, his lunchbox filled with rice rested on his lap, a single plum rested on top. So much for letting a 7-year-old prepare his lunch. 

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

When in doubt, do a flashback

The homeroom teacher went on and on about the upcoming field trip that Friday. From what the teacher mentioned, they were going to attend a popular kendo show where they mixed comedy and the ancient art of kendo. None of them expected much since every school in the Beika region had been invited, including the elementary schools, meaning the comedy show would be pretty vanilla. Since homeroom went on for longer than expected, math class started as soon as the teacher walked in, leaving no time for the students to socialize. 

Gintoki had expected high school to be hard (it tends to be when instead of getting an education you fight in a major war), but this was too much for him. Immediately after walking in, the teacher had asked him to go up to the board and solve a problem.

"It shouldn't be too hard, I'm sure you saw this last year," She had said, mocking him (not really, that's just how he felt it), as the embarrassed teenager struggled to figure out what to do. 

The only algebraic material he was any good at was addition and subtraction. Especially subtraction. He had gotten really good at it after years of losing at pachinko. As much of an idiot as Zura was, he knew some math, he even tried to teach the troops during the Joi war but no one paid much attention to him. Now he wishes he had.

Gintoki felt a big, obscure cloud of dark energy forming behind him. Were his "classmates" making fun of him? How dare they! Don't they see he's the new kid? Why are none of the hot chicks running to talk to him dammit!!!

No one cared, in fact, it was all in his imagination.

After embarrassingly standing at the front of the class for seemingly an eternity and a half, the teacher finally decided to return him to his seat. As he made his way back he heard some slight snickers from his new classmates.

'How embarrassing!' Was the only thing on his mind as he tuned out the teacher's voice, 'I bet they all think I'm an idiot now. This sort of thing only happens to the class loser, why is this happening to me, the former White Demon?!!!!!"

These thoughts plagued his mind all the way to the end of period. If math class wasn't embarrassing enough, the next class in the curriculum was chemistry, something he had never heard of before.

The perm-headed teen expected the worst outcome, like being asked to perform an alchemy circle, but luckily for him, the chemistry teacher was absent that day and they had a free study period. Gintoki learned the wonders of cyanide from his textbook after looking up ways to possibly murder anyone who mocked him after the math fiasco. 

As the silver-haired man tried to avoid looking at anyone in the eyes, he heard a tiny female voice whispering behind him, trying to get his attention, "Psst, Sakata-kun, heeeey. Sakata-kun."

'Just ignore her, I bet she just wants to bully you, but you won't let her, no sir. I wasn't forced to come here to get bullied by teens,' Gintoki thought, still hung up on the embarrassing moment, 'There's no way anyone could've done that, it had way too many Xs and Ys. Not my fault Y wants to be isolated from its ex-'

"DON'T IGNORE ME YOU JERK," The voice shouted moments before he was forced out of his seat by a kick directed to his back. When he looked up, everyone was staring at an enraged girl. She had short, light brown hair with a hairband at the top to keep it from getting in her face.