Pay With Your Heart - Chapter 474

He was confused, so he asked, “I have a car, a house, good-looks and money. What am I lacking in?”

He Lang died by his own hands for the sake of his imperial younger brother’s ambition, whom he loved. He was offered to be reborn in exchange for giving up his past romantic feelings. Reborn without the burden of his romantic feelings, he brings with him a manual to new worlds. He wholeheartedly followed the instructions of the manual to complete the tasks, not knowing that the originally slag gong was blackening…
He pleaded to his affectionate Emperor brother to release him, he pleaded to the paranoid prisoner next door, but until the end he remained baffled.
In the end, he discovered that the full name of the manual was – “Slag Shou Cultivating Manual”
Σ (っ ° ° °;) っ!

- Description from Novelupdates

Chika Satomi is a beloved and beautiful girl in the class known as the ‘Angel of Peace.’Ichinose Sōma, who is a fanatic about making sweets, asks Chika to be a taster for him after school when he makes some sweets.Saying things like,「I also want to try various things――」「…Ichinose-san’s embarrassed expression is really cute…」Sōma ends up watching over Chika, who keeps teasing him.Though usually passive, for some reason, Chika teases Sōma with a sly smile, showing her mischievous side only to him, and as a result, Sōma’s after-school hours become filled with sweetness!?A sweet and thrilling romantic comedy with a naughty angel woven together by confections!

Long Fei, a cross-timer and doujin, is an otaku who traveled to another world. In the original world, he was an otaku fan of Gundam and military science fiction.

He died in an accident and was reincarnated into another world. The Gundam works he had read before his death and the techniques in various military novels could be brought to another world.

How would he use the Gundam that Long Fei created? What waves can be caused in this different world?