Maybe she's just really tired from a long day of adventures.
It could be that she needs to sleep to restore her energy for the next exciting part of the story. Sometimes characters need rest to keep going. Also, it might be part of a plot device to introduce a dream sequence or a new development when she wakes up.
The manga girl sleeps because it's a natural part of life. Maybe she had a tough battle or a lot of thinking to do, and now her body and mind need to recharge. Or perhaps it's a way for the author to build suspense and make us wonder what will happen when she wakes up.
Chapter 391, "Seal The Core", is the clearest early answer because it turns Godsthorn's situation into a concrete plot event. The chapter gives readers a real answer by opening on Dean Godsthorn didn't flinch as Dean Veyra stepped out of the... and ending on They cleared it out in time." "You think they were stalling?" "Buying....
Chapter 519, "Provoking Them", is the clearest early answer because it turns Damien's situation into a concrete plot event. The chapter turns that into something concrete by moving from The forest no longer felt calm. to He drove his fist so hard that his knuckles tore through bone and out.... What makes it stick is that the chapter closes with Because now, he was ready to hunt something stronger., which gives the main cast a stronger narrative position and pushes the technology upgrade onward.
Chapter 132, "Leaving The Forest of Twin Disasters", is the clearest early answer because it turns Keith's situation into a concrete plot event. The chapter gives readers a real answer by opening on The three sat around the campfire, its warm glow casting flickering... and ending on You distracted the Drake?" she asked, narrowing her eyes.. In story terms, the chapter closes with Damien nodded, his expression unreadable. As the fire continued to crackle, he felt a small sense of relief.
Chapter 120, "A Wrong Decision II", is the clearest early answer because it turns Keith's situation into a concrete plot event. The chapter turns that into something concrete by moving from Keith and Narna struggled against the overwhelming pressure crushing... to Keith spun around to face Narna, his frustration boiling over..
Chapter 214, "Testing The Others", is the clearest early answer because it turns Damien's situation into a concrete plot event. A useful checkpoint is the way the scene starts with The demons will come at you all of you don't go to them." Damien... and follows through with Since we're done here, let's get moving." Damien began walking..
Chapter 500, ", Alliance 400 Worlds", is the clearest early answer because a shaky connection becomes usable in the plot. Early on, The Alliance Government did even better than Gu Hang had imagined.. By the end, Under normal circumstances, this would not be easy to achieve..
Chapter 141, "Demon Infestation Mission II", is the clearest early answer because it turns Damien's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Damien moved into the shadowy recess of an alley, checking for any... and follows through with Please, die!" he said, charging into the fray..
Chapter 10, "Running and Hiding", is the clearest early answer because it turns Damien's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Damien was still admiring the beautiful bluepanel that displayed his... and follows through with Without delay, Damien hid between the roots, finding a way to get....
Chapter 373, "The Second Trial Begins", is the clearest early answer because it turns Elias's situation into a concrete plot event. It opens with The first phase is now complete!" The announcer, Dean Oryll's voice... and closes on The demons began to emerge—eight of them, clawed, armored, already.... The key payoff is that the chapter closes with (07:05), which gives the main cast a stronger narrative position and pushes the power growth onward.
Chapter 353, "Reinforcements Arrive", is the clearest early answer because it turns Reinforcements Arrive's situation into a concrete plot event. The chapter turns that into something concrete by moving from Arielle's blade cracked against bone, again. to She ran—stumbling into Aquila's flank, dragging her legs up over the.... What makes it stick is that the chapter closes with Arielle coughed.