ONE FOR ALL: The Story

One for All, arguably the strongest quirk present in the Boku no Hero Academia universe has its powers passed down and amplified by eight different users and the final culmination being the hero of the story Midoriya Izuku. Today we are going to see how this quirk came into existence and what has each holder contributed to bringing this quirk to its ultimate final form. Things might get a bit nerdy but hold tight it will be all worth it.

So let's start with the origin of One for All. To put it in simple words One for All was created by All for One. All for One as we all know has the power to hold multiple quirks to use and transfer them at will. His younger brother Shigaraki Yoichi was against his brother's ways of taking others' quirks and using them to his liking. AFO pitied Yoichi for not having a quirk, so he forced a power stockpiling quirk onto him. Little did he knew Yoichi had a quirk that could be transferred from one person to another. Yoichi's original quirk and the power stockpiling quirk merged to form the quirk One for All as we know now.

Yoichi tried fighting AFO but was defeated and captured. A resistance movement against AFO found Yoichi. At first, they wanted to kill him as he was the brother of AFO but decided not to after realizing Yoichi was against AFO himself. Yoichi transferred his quirk to the leader of the resistance. Not much is known about the second user other than that he was the leader of the resistance against AFO and he passed down the quirk to one of his juniors.

For the third user, we know that his quirk is named "Fa Jin". His quirk stores up kinetic energy and releases it in one go which can be used in mobility or to deliver a blow. This quirk was very helpful for Deku in defeating Lady Nagant. The quirk was transferred to the fourth user Shinomori Hikage. Hikage had the quirk "Danger Sense", it is exactly what it sounds like it warns you if there is any danger around. Deku got it during the liberation army war against Shigaraki Tomura and immediately passed out from the pain in his head. Hikage realized early on that he would not be able to defeat AFO so he dedicated his life to developing One for All and passed it on before his death. Hikage inherited One for All at the age of 22 and died of old age at 40. Seems a bit odd right, hang on, everything will be clear by the time you finish reading this article.

Hikage passed on the quirk to Banjo Daigoro (Hero Name: Lariat). Daigoro is the original user of the quirk "Black whip" which we saw Deku manifest during the training battle against Class B. Daigoro was the first of the vestiges to guide Midoriya and tell him that he will have all his predecessors' quirks. Daigoro was killed by AFO in an attempt to steal OFA, but couldn't as he passed it down to one of his subordinates En during the battle. The Sixth user En had the quirk "Smoke screen" which also works exactly as the name suggests creating smoke. En was also killed by AFO to steal OFA but was again unsuccessful and the quirk was passed onto Shimura Nana.

Shimura Nana was the mentor of the greatest hero All Might. She had the quirk "Float" which allowed her to float in the air. Shimura was the first of all the predecessors to choose her successor at a young age and mentor him from the start. Shimura transferred the quirk quite early and this allowed All Might to get accustomed to the quirk and use it to a much higher potential than any previous users. Shimura also died at the hands of AFO. She was the last OFA user to die at the hands of AFO.

Yagi Toshinori or All Might as most of us know him is the strongest hero to exist till now. He was quirkless to start with and inherited the quirk at a younger age from Shimura Nana. All Might fought AFO twice and defeated him both times but suffered major injuries, the battle in Kamino being the last one that led to his retirement. Before all this, All Might had already started searching for his successor and decided to become a teacher at U.A. but before he started his task at U.A. he found Midoriya Izuku a quirkless boy with a strong desire to help people. All Might decide to pass on OFA to Izuku after watching him jump to save a boy being attacked by a villain even though he was quirkless. All Might used OFA for 40 years.

As we all know Izuku is learning to use OFA at its full potential at his own pace. He can utilize up to 45% power of OFA without damaging his body and can use all the quirks inherited in OFA simultaneously (although we never saw him using the second user's quirk)(Manga). Izuku is the only one who has been able to use the multiple quirks inherited in OFA.

It has already been revealed in the manga that Izuku will be the last user of OFA, let's see why it is so. As we said earlier every user is a vessel for OFA. A person with a quirk can be said to be a partially filled vessel and a quirkless person can be said to be an empty vessel. Over the years One for All has grown so much that only a quirkless person can hold it and if given to a person with a quirk it will shorten their lifespan drastically. This was the reason that the fourth user Hikage died of old age at the age of 40 and All Might is still alive after holding OFA for 40 years. In the current timeline of Boku no Hero Academia universe the quirks have become so complex and multiplied so much over the years that finding a worthy person who is also quirkless is close to impossible. And even if you find a suitable person the quirk has gotten so strong that the first-time use of the quirk will kill the person.

We are yet to see the full potential of One for All and the quirk of the second user being kept a mystery indicates something very special is kept in store for us. I can't wait to see when Deku goes all out against AFO/Shigaraki Tomura and for anime-only watchers to hold tight things are going to get interesting.