Saitei Ouji-tachi ni Yoru Koui Sou "Jou" Sen: Binbou Kuji no Koui nante Dare ni demo Kureteyaru!

The illegitimate fourth prince, Sugen, thought that his current status was perfect. However, one day, he was told to become the next Emperor. Sugen, hating the thought of having to toil for the Empire, asked "Why can't my brothers do it!?" to which the Emperor replied, "They have no determination." And so, the bloody battle of giving the other siblings the inheritance started between the determination-less princes and princess.

(Source: Shousetsuka ni Narou, translated)