If you'd like me to add or modify anything, please let me know!
It seems you're referring to the Japanese title (少年が大人になった夏), which translates to "The Summer a Boy Became an Adult" — and you added "مترجم" (Arabic for "translated/subtitled").
The answer is . We, the audience, are the ones who have already grown up. When we watch the protagonist catch his last firefly or say goodbye to his first love, we are not mourning his loss. We are mourning our own past selves.
Taro was initially disappointed, but he soon realized that this was an opportunity for him to gain some independence and experience the world on his own. He spent his days helping out at the beachside house, where he met a group of interesting characters, including a young woman named Yuna who was working as a part-time lifeguard.
