( 10 years ago)
mom:kyouka come here
kyouka: yes mom?
mom: the ring I will gave you now it was your fathers last memory.when he died he give me this ring as a memory but he also told this ring is not normal it has special abilities so kyouka I want you to keep this ring.
then kyouka mom give her this ring
kyouka: ok mom I will keep this as a treasure
mom: remember never lost it .it is your father last memory
then after 10 years she always wear this ring on her hand but one day when she got into train suddenly a light come from this ring and she found herself in past
(present)
kyouka: now I understand I come here because of the ring
ken: what are you talking about?
kyouka: ken I will tell you something important but plz believe me .......