Time line for My Hero Academia X Monster Musume Fan-fiction
2025: the human government introduced the monster species to the world at large and created the first inter-species exchange bill.
2100: the inter-species exchange bills have finally been balance to have all species share the same rights from birth to marriage and even death. Some small communities have yet to fully integrate but all live in relative peace.
2150: a human child is born in china with chem-luminescent skin, or for better terms skin that light up without giving off heat.
2150-2200: after some quick thinking by the world governments and help from the previously established Inter-species bills most humans who tried to cause trouble with quirks where quickly shut down by the larger and stronger of the monster species. Several however where still to strong for even giants and ogres to handle, this cause the emergence of a new career path to emerge Hero's.
2250: 90% of the world population now has powers in the forms of quirks or gifts from their heritage as a monster. The 10% left are the small amount of humans left whom don't have quirks