Naho got into a fight with Kakeru on New Year's Eve, and never managed to apologize to him before he passed away. At least, that's what the letter from the future says. However, Naho now believes that she's capable of dealing with whatever may come up, and faces New Year's Eve head-on.
If I'd only realized how everyone 
felt sooner, I could've helped Kakeru.
Hätten wir das früher gemerkt,
dann hätten wir Kakeru helfen können.
Si me hubiera dado cuenta antes,
los habría apoyado.
Si me hubiera dado cuenta antes,
los habría apoyado.
Si on l’avait su plus tôt, 
on aurait sans doute pu l’aider.
Если бы мы поняли раньше,
что он чувствует, могли бы ему помочь.