The most relevant of what happens in the Fourth Volume or World, in this case would be that of Kobayashi-san Chi no Maid Dragon. The most important moments will be discussed, as well as the characters that should have more relevance and the respective arcs. Preferable to read before or after finishing Volume 4.
--------------------------------------------------
W͇o͇r͇l͇d͇ ͇4͇:͇ ͇K͇o͇b͇a͇y͇a͇s͇h͇i͇-͇s͇a͇n͇ ͇C͇h͇i͇ ͇n͇o͇ ͇M͇a͇i͇d͇ ͇D͇r͇a͇g͇o͇n͇
I͟s͟e͟k͟a͟i͟ ͟A͟n͟o͟m͟e͟n͟o͟s͟ ͟A͟r͟c͟
Important Characters:
-M
-Tohru
-Kanna
-Fafner
-Lucoa
-Elma
-Kobayashi
-Sora
-Mira
-Dux
-Lami
-Arnna
-King
Important events for the story:
-The most important is that Sora is one of the strongest mortal beings in the whole story, already in itself this is strong, with what will be explored more next and will talk more about her, she will still get a power that would rival the strongest beings, also Sora becomes key in the most important arcs, she has an important role that without her the story could fall apart and that would be the end of everyone. She will have an important role in the MY Rescue Arc and in the XYZ Arc.
-Mira also has an important role in the story, also this would be one of the most powerful characters that exists in the whole story of M no Monogatari, in the same way her most important participation would be in the previous arcs I mentioned, since Sora and Mira have a more important connection in the future, literally Sora would be a kind of caretaker seeing the potential that Mira has.
-The power Mira has is obtained externally and it's not something from her, somehow something fell into her giving her all that power and aspect.
-Here we start to give the basis of what we want to achieve for the future, this was seen in the part where the story of the past is told, of the Anomenos Family, when Sora fights against Kasper, here we talk directly that there are 2 powers synchronized and working together at the same time, this will become more relevant when we want to unite several powers to make them one.
-Here M has another way of growing, leaving behind what he thought was right to become more mature so to speak, his way of thinking and seeing things here begin to influence a lot in his behavior.
-As I said before in Canonical Events of World 3, in that volume M discovered that he likes people with personality like Tohru, for this reason M tries to make an effort to please that dragon.
-Later in the future, thanks to Iruru, M would finally get an immunity or rather she would leave behind that ugly habit of being disgusted every time she sees a person with big breasts. Literally with the passing of history, M would become almost impossible to receive stimulation, either mentally like getting nervous or shy as well as flesh and muscle stimulation xd. In the end the only thing that would make him get a little out of his mind would be something that he really didn't expect and has never seen before.
-Small spoiler for the future, in the M.U.G.E.N. Arc, as participants will be Kanna and Tohru on M's side, Sora will also be included but only as a spectator, rather she was invited to check that nothing bad happens, as I said this character is one of the strongest that even has relevance as a guest to see such event.