The significance of fan service in "Chained Soldier" or any other work can be multifaceted:
Narratively, this is framed as a transactional curse. Yuuki often reacts with embarrassment or dread, while the female chiefs (Kyouka, Himari, etc.) display a mix of clinical obligation and hidden blush. This creates a power dynamic reversal rarely seen in mainstream anime: a male protagonist who is physically and socially subservient to a female-led hierarchy, with his suffering (and arousal) being the comedic and titillating payoff. Chained Soldier Fan Service
: To maintain this power, the master must provide a physical "reward" to Yuuki after a battle. Narrative Justification Chained Soldier — Fan Service Report Overview