My assumption so far :
Shizuku is Takuto's half sister. She's a daughter of his dad's mistress. That's why Takuto said in the car he couldn't have what he wanted and preferred to be in Riku's family (to be able to love Shizuku). Riku's parents know this secret, that's why Riku's dad gave him a condom though Riku told him Shizuku was Takuto's girlfriend then Riku's mom got mad at him.
Shizuku has had a serious heart disease since she was young and become worser and worser till she needs the regular treatments after school. Takuto is the one who takes her to the hospital after school. So, they fake they're going out to hide her illness from Riku. That's why she has to inform Takuto first before going home with Riku on the day Riku asked her to go home together but they didn't do it because Riku had to help Yako and Umimi study.
The evidences of her illness are : Shizuku got chest pains every times she and Riku have physical intimacy. After their first kiss, Shizuku did get her chest pain. She ran away holding her chest, cried and said to herself she should do it sooner. She got sick easier till she could not undress herself and asked Riku to do it for her the day before she disappeared. The bruise on Shizuku's neck which Riku mistakenly thought was a kiss mark actually was a result of a puncture in her neck because her illness was too bad to puncture her arm. It's the treatment for patients who are in very bad conditions.
In chapter 1, Shizuku came to Riku's house after she and Takuto went to a cafe and then the hospital because on that day her doctor told her she's going to die soon. That's why she went to Riku's house desperately. Takuto sent her a message to cheer her up saying there will be an exhibition but she's too sad and turned off the phone.
Shizuku knows she's going to die in the hospital because the surgery is just to buy her some time so she said to give the rest of her time to Takuto.
It seems we cannot avoid Shizuku's dead. If there is no miracle, hope she dies happily in Riku's arm.
Shizuku is Takuto's half sister. She's a daughter of his dad's mistress. That's why Takuto said in the car he couldn't have what he wanted and preferred to be in Riku's family (to be able to love Shizuku). Riku's parents know this secret, that's why Riku's dad gave him a condom though Riku told him Shizuku was Takuto's girlfriend then Riku's mom got mad at him.
Shizuku has had a serious heart disease since she was young and become worser and worser till she needs the regular treatments after school. Takuto is the one who takes her to the hospital after school. So, they fake they're going out to hide her illness from Riku. That's why she has to inform Takuto first before going home with Riku on the day Riku asked her to go home together but they didn't do it because Riku had to help Yako and Umimi study.
The evidences of her illness are : Shizuku got chest pains every times she and Riku have physical intimacy. After their first kiss, Shizuku did get her chest pain. She ran away holding her chest, cried and said to herself she should do it sooner. She got sick easier till she could not undress herself and asked Riku to do it for her the day before she disappeared. The bruise on Shizuku's neck which Riku mistakenly thought was a kiss mark actually was a result of a puncture in her neck because her illness was too bad to puncture her arm. It's the treatment for patients who are in very bad conditions.
In chapter 1, Shizuku came to Riku's house after she and Takuto went to a cafe and then the hospital because on that day her doctor told her she's going to die soon. That's why she went to Riku's house desperately. Takuto sent her a message to cheer her up saying there will be an exhibition but she's too sad and turned off the phone.
Shizuku knows she's going to die in the hospital because the surgery is just to buy her some time so she said to give the rest of her time to Takuto.
It seems we cannot avoid Shizuku's dead. If there is no miracle, hope she dies happily in Riku's arm.