Sekai Saikyou No Kouei: Meikyuukoku No Shinjin Tansakusha

Okay, so our main character is a workaholic with a demanding boss, who are both together when a bus crash kills them both. Something something isekai something something skill points something something adventurer's guild something something dungeon exploration. Look, you've been here long enough to know how it , the demanding boss becomes a Valkyrie and the MC, not wanting to work under her, decides to go solo. He soon must choose a class that his character will work as, and decides on "rear guard". However, he soon finds that a rear guard is actually a fairly rare job - and one he may just be able to excel at.