I recommend the sci-fi time-space travel novel, I Am Not The Dao Ancestor, to you. Although it was not completely consistent with the plot described in the paragraph, there was indeed a beggar in the book who obtained a disc with the help of the protagonist, Hong Yi. The disc contained the Jade Disc of Fortune. Although the system did not require the protagonist to join the army, the protagonist did need to constantly improve his strength through the system and complete various missions. I hope you like this fairy's recommendation. Muah ~😗