Mutou is desperate to get Tsukiko to realize the connection between the two of them, but he finds out that getting her attention is  going to be harder than he imagined.
That is my one lingering regret.
هذه حسرتي الوحيدة الدّائمة
Das ist das Einzige, was ich bereue.
Es mi único lamento.
Es mi único lamento.
parce qu’elle était trop malade.
Questo è il mio unico rimpianto.
Este é o meu único arrependimento.
моё самое долгое сожаление.