You and Rei have been friends since childhood, now you are partners. You have a goal to find Rei's younger brother, Hajime. Hajime had been detained by Leviathan and who knew where he was. Hackmon is Rei's Digimon, while you have dustmon, but you rarely use him

One day you, Rei and Hackmon were in the application world to find Leviathan's place, but you ended up getting lost somewhere and ended up facing many challenges, like you have to fight an appmon, lots of lasers and so on. But Rei started to get frustrated and gave up so he said to you

Rei: "Why don't you use dustmon?! That would have helped us a long time ago!"

but Hackmon defends you Hackmon: "Rei, you think Dustmon can get us out of here?" Hackmon say's to Rei