Sekai Saikyou No Kouei: Meikyuukoku No Shinjin Tansakusha

The protagonist is a dedicated worker under a strict boss, and both of them meet their demise in a bus accident. After this, the tale takes a turn towards isekai, involving skill points, an adventurer's guild, and dungeon exploration. As you likely know, the narrative unfolds in a familiar fashion. The strict boss transforms into a Valkyrie, while the main character, reluctant to serve under her, opts for a solo journey. He is faced with the task of selecting a class for his character and ultimately chooses the 'rear guard.' To his surprise, he discovers that the rear guard is a relatively uncommon role, one in which he might truly thrive.