Capítulo 300: Inside Kretos's memories

After listening to Kretos's story Tsukiko now had a basic understanding of how strong Kretos was. If he was this strong then how come he had difficulty fighting the other demon lords? 

'Was he holding back each time he fights...' Tsukiko looked at the exhausted Kretos and thought about his battle loving personality. 'If it's this guy that could be a possibility.' While she was thinking, a very scary notion came to her. 'Could it be this guy is improving while battling?!' That would mean every time he battles he gets significantly stronger, which would also explain his love for battle. 

When Tsukiko thought of this a lot of her questions finally had answers, but she also felt like she was missing some crucial information. 

...

Kretos and Tsukiko talked for a few hours until Kretos finally felt a bit sleepy. Seeing as he still couldn't sleep, Tsukiko offered to help. 

'I could use a sleeping spell on you.'