Reborn as a Space Mercenary: I Woke Up Piloting the Strongest Starship! (Light Novel) Vol. 16 by Ryuto, Tetsuhiro Nabeshima

When Hiro returns to the imperial capital, Chris has a lot of questions. In fact, she's set on grilling him--less about his mercenary adventures, and more about Colonel Serena. If Serena herself gets wind of Chris's prying, there's no way she'll let Hiro smooth things over. In fact, the prim and proper colonel will probably blow a gasket.
But Hiro will need to deal with something that poses a much greater threat than Chris's pointed questions: an assassin who's found their chance to strike. The situation has gone from awkward to deadly--and Hiro will have to fight tooth and nail to leave the capital in one piece!