If somebody asked Tadaomi Karasuma at what point he fell in love with Irina Jelavić, he would find it impossible to answer.
Because there was no one moment. Over time, the assassin had grown on him (like a fungus, he'd add, just to see Irina puff her cheeks and complain) until at last he realised that a life without her around would be far too dull.
So he had given her his home. Given her a job. Made every effort to help her put down roots in Japan.
And finally...
"Will you marry me?"
He had given her his heart.