Systems, devices, and related methods for fastening tissue

An endoscopic tissue fastening device may include a body having a first portion and a second portion arranged alongside the first portion. The second portion may extend distally of the first portion and may terminate in a distal end face of the body. The device may further include a tissue fastening assembly having a fastening head with a proximal end and a distal end. The fastening head may be deflectable at a location between the proximal end and the distal end of the fastening head. The tissue fastening assembly may be received within a lumen of the body. Further, the body may be moveable between an unarticulated configuration and an articulated configuration. In the articulated configuration, a central longitudinal axis of the second portion of the body may be substantially parallel with a central longitudinal axis of the tissue fastening assembly.