The person who called Ryuto to the gym at night was actually Maria. She confesses her desperation to become Ryuto's first, even if that means dressing and acting like Runa. Ryuto is shocked. As the two talk it out, someone else watches from the shadows.
If she confessed her feelings to you, 
then she must have really meant it.
.إن اعترفت بمشاعرها لك، فذلك يعني أنها جادة حقًا
Ihr Geständnis sagt mir,
dass ihre Gefühle für dich echt sind.
Je pense
que ses sentiments sont sincères.
Se ti ha confessato i suoi sentimenti,
devono essere sinceri.
Se ela se declarou a você,
então ela deve ter falado sério.
Если она тебе призналась,
то сделала это от всего сердца.
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