Sekai Saikou no Ansatsusha, Isekai Kizoku ni Tensei suru

Both are really similar in these forms : - Isekai world - Reincarned MC keeping his previous mind/souvenirs. - Want to learn extra quick to be the best - Harem feels with a lil girl magic master and then lot of female around  

Similar art style and similar energy. MCs are both isekai'ed into their new worlds and are raised with a pure personality (i.e. they're not creeps). They both retain their memories so they're too OP with their ideas of modern tech, but they still grow a lot as they get more familiar with the new world. No need for Shokugeki no Soma because they got cooking skills and waifus in this show too. 

Theme is reincarnation. MC is born with high specs and work towards a goal of destroying certain entities while recruiting a harem full of baddies to fight for his cause. 

The MC reincarnates into a new body in a family that has the same profession as the MC had in his previous life. In Sekai Saikou the MC is an expert assassin and in his new life, he gets the mission to assassinate the hero. In Isekai Yakkyoku, the MC is a doctor and an expert in the medical field, and he sets it upon himself to improve medicine in this fantasy world. Both shows give me similar vibes in how they introduce the characters, and how they react upon reaching the new world, living a life as the son of an aristocrat. 

Both shows have an MC who assassinates their targets in a fantasy world. In the world's greatest assassin, the assassin got Isekai'd into this world to assassinate the hero. In the executioner and her way of life, the executioner executes people who got isekai'd into her world. 

Both shows are isekais, where our main character is betrayed and turns into an OP white hair dude, both are merciless due to their own nature and both uses guns, also both find a group of girls that with those will carry out their misdeeds, esthetically the shows also look similar, from the title, the OP and tha animation (but in the last one I think that is better done in the Aristocrat anime) 

-both are focused on the assassination of nobles that are doing evil deeds -both MC's are big brains 

S: Both MC are reincarnated as children Both MC hide their powers Both MCs have overpowered skills Both MC have female groups (harem) Both series are set in fantasy world D: Sekai is modern isekai v seiken is fantasy isekai 

Similarities - Both MCs are talented assassins - Both MCs have a female companion - Both MCs hide their trade using a proxy business (perfume/hair salon) - Both worlds have forms of magic techniques (mana/cultivation) Differences - Scissor Seven MC tries to carry his job out but it always fails successfully (weird endings) - Scissor Seven MC doesn't have a harem but his female companion is a tsundere/yandere - Scissor Seven MC doesn't reincarnate but loses his memories so he starts fresh in the beginning - Finest Assassin has vast worldbuilding involving kingdoms VS Scissor Seven worldbuilding is enclosed on an island with the habitants being clients and targets and occasionally in the technologically developed nation Istan read more 

Similarities - Both MCs are contract killers/assassins - Both MCs have a harem - Both MCs don't have emotion (in the past life) - Both MCs have experience in close quarters combat and firearms - Both MCs use snipers - Both MCs have no emotion and are treated like tools Differences - MC in Grisaia doesn't die and reincarnate - Sekai world is in MMORPG fantasy world - MC in Sekai doesn't have army backgrounds - Grisaia is based in a Japanese world 

Similarities - MC is a contract killer - Both series have magic - Both worlds are MMORPG fantasy - Both MCs have no emotion and are treated like tools Differences - Magic High doesn't have harem like Sekai - Sekai MC is reincarnated in a new world 

Similarities - Both MCs are contract killers/assassins - Both MCs have a harem - Both MCs don't have emotion (in the past life) - Both MCs have experience in close quarters combat and firearms - Both MCs use snipers - Both MCs have no emotion and are treated like tools Differences - MC in Grisaia doesn't die and reincarnate - MC in Sekai doesn't have army backgrounds - Sekai world is in fantasy world - Grisaia is in modern Japanese world 

They are both isekai with a great animation quality 

- Both are Harem - ML are very powerful and strong - Both don't have annoying characters (from what I can recall.) - Short animes - Both ML have a hard time getting people to recognize them until proven wrong.  

Both are about someone who was the best and got betrayed then reincarnated in another world. Both are a good watch. 

Both MCs are reincarnated as a child in the royal family, over powered 

They both have magic in it  

Similarities - MC is a trained contract killer - MC has no emotions - MC is experienced in close combat/firearms specialist Differences - MC in Jormungand is a poor kid that gets taken in - Sekai is a reincarnation series set in a MMORPG fantasy world 

Same Creator Same Anti-Hero vibes Mc is an anti hero Ecchi Vibes Both feel really similar but I would say Sekai Saikou no Ansatsusha, Isekai Kizoku ni Tensei suru is better written  

The protagonists have white hair, evolve quickly and the environment of both works is very similar. 

Sekai Saikou no Ansatsusha is relatable to Fate/Zero due the main character nature. Kiritsugu resembles, somewhat, this greatest world assassin by also being an skillful person while coming to contracts and "hitman" portfolio. Important to be said that, yet, Fate's mc seems to be more carrying and does have a slightly clearer goal, although, kinda distorted and idealistic unlikely to happen. I don't know much about the "Sekai Saikou no Ansatsusha" development but both figures have some serious chaotic neutral alignment, after all, there's hardly any ego traits in their persona, making hard to them being their judges besides using logical reasoning. In the end, most of times, they can only be slaves of something and doesn't like much the trouble dealing with emotional behaviour. Regardless, both animes seem to deal rly good with "seinen fantasy" genre (still, interesting to mention, I did notice some evident sensualization in the more recent anime which is rare to find in Fate/Zero- even so, a common trait in the rest of the Fate franchise). read more 

Both MC reborn in another world with memories from their past life. Both MC was part of a sect in their past life. Both MC are OP af Both MC have a girlfriend and want to marry her 

MC gets reincarnated in a fantasy world, overpowers his foes with his past knowledge surrounded by female characters 

One assassin guy and harem of of cute assassin girls. Both are quite edgy and give similar vibes. 

Both anime deal with a group of assassins from a fantasy world killing evil people for the sake of their empire/kingdom. The group is mostly conformed by girls, but has a male protagonist.  

Reincarnated main character just vibing and getting stronger, Knows its target audience and delivers on every important aspect for it 

while its not Isekai both anime play the lead of highly skilled assassins. 

although very different the two main character are very similar Lugh and Goburo are very similar both where fighters/ assassins in their last life killed on the battlefield both are reincarnated with their skills from their last life both are very tactical aware and cruel to protect themselves or farther their goals both have parts of their body altered one with surgery and the other a prosthetic arm that enhanced their bodies  

Similarities - Both MCs are contract killers - Both MCs have no emotion - Both MCs are skilled in hand to hand and firearms - Both MCs discover nefarious plots Differences - MC in Darker than black doesn't reincarnate - Darker than black isn't a harem 

Both Goblin Slayer and Assassin involve sociopathic MCs who only care about the singular task they've been given. While they both take place in worlds of swords and sorcery, their settings are different enough to not keep the shows from feeling the same. A fun part of both stories comes from the fact that both MCs are outwardly OP in nature. While both are badass in presentation and execution this does not come from simply having the more OP skills or being overpowered for overpowered sake. Both are OP within their universes because they have a level of proficiency and expertise that allow for them to have the skills and knowledge to be experts in their fields. This is a positive for both shows in a genre that more so than not simply allow MCs to be overpowered for overpowered sake.  read more 

Both shows involve a more pragmatic MC in a fantasy world dealing with hero(s) that cause problems. In the case of Assassin, the MC is tasked with killing the hero in exchange for being reincarnated while Shield Hero sees the MC being outcast from the rest of the heroes for reasons. While I do not believe both are of the same quality, I do think if you liked the MC in one, you may like the MC in the other. They also deal with more competent worlds where not everyone is a complete idiot, so that is refreshing and can help with watching. 

Both of these shows involve an MC who is not a prototypical good guy. The difference is that why Assassin shows an MC who is trying to be more of a person with their own thoughts and opinions, Overlord dives into an MC who all but removes their humanity from the start and goes full villain. Why both shows take different paths, their goals are somewhat similar and may make the watch at least worth a try. Also both MCs are OP so that can scratch the power fantasy if that is what you are looking for. 

Similarities - Both MCs are top assassins - Both MCs have no feelings and always succeed in killing their target - Both MC have crazy OP abilities - Both MC are similar ages - Both run away from law enforcement Differences - Sekai is a reincarnation story - MC in Sekai is sent into another VS. Golgo isn't - Golgo is a Japanese VS. MC in Sekai is an American - Golgo kills witnesses