Inuyasha and Sesshomaru are transported to the world of The Seven Deadly Sins

The plot gods have for the desire of entertainment transported Inuyasha and Sesshomaru to the world of The Seven Deadly Sins, both have their swords, and are explained to them by the gods the world, they both get involved with the story. This is both of them at the end of the story.

Scenario 1: This is at the beginning of the story of the seven deadly sins.

Scenario 2: This is at the middle of the story of the the seven deadly sins

Scenario 3: This is at the point that is in between the beginning and the middle of the story.

They are way too slow and fragile to have any business trying to fight anyone of note, though Inu Yasha could be a very powerful clutch character with his dimension-dumping/slicing Meidou Zangetsuha and his ability to oneshot youkai by sensing and slicing their Youketsu might translate over to demons as well. And if Tessaiga can absorb the power or abilities of any demons or gods (or demonic/divine artifacts) that he manages to land a killing blow on, that could be a pretty hefty boost for him. Similarly, Sesshoumaru's poison and Bakusaiga's expanding damage ability could be very effective as well if he is strong enough to so much as scratch his opponent. Inu Yasha's abilities to break or bypass forcefields with his red and diamond Tessaiga, respectively, might be useful too (did anyone use barriers in Seven Deadly Sins? Mmmmaybe Merlin's former student, or that barrier Demon Melidas put around himself?), and Sesshoumaru's one-time Get Out of Death Free Pass shaped like a sword could be very useful, if only to make a certain someone's recent sacrifice even more pointless.

The problem is that neither brother is fast enough to keep from getting blitzed by the upper tiers in Seven Deadly Sins. In a total reversal of expectations considering their respective personalities, while the sour hothead Inu Yasha is often willing to think out of the box and work with others to take out powerful opponents, the stoically noble Sesshoumaru is a total Leroy Jenkins 150% of the time and refuses to contemplate any strategy that doesn't involve immediately walking up to whatever needs killing and introducing himself to them sword/claw/fang-first.