Hey so I was reading this a couple of days back when I was free but don't remember the title now. The plot: dude reincarnated into a royal family as the 13th prince. He is given a demonic sword of leviathan by his elder brothers as a present given his SS rank water affinity and he manages to use the sword without dying thanks to that. At the last chapter he gave his maids mother a job as a guard at the rear gate so that the maid doesn't have to sell herself in the red light district for extra income and also sends of a subordinate to a flood hit area to buy up all the land available for sale before the greedy merchants can at a fair price. In the description it is said he was given a fief(or mansion) where he lived freely but after the death of elder brother (crown prince) he is chosen as the next heir since he's the most capable among his brothers and became the most powerful among emperor's.
https://forum.novelupdates.com/threads/forum-rules.29321/ please refrain from using ambiguous, lazy title.
I had written a little bigger title there I don't know what happened for it to be shortened to a word