Once again, spoilers lurk beyond this point, especially in the story-specific sections. You've been warned.
On 'Eyes of the Heart'
- Taka refers to Kana as imouto (little sister) and adds the affix
'–chan' ('little one', in this case).
- It's a far more intimate form of address, in Japanese, to address someone
by their first name without using an affix. This is why Kana finds it so
hard to call her brother 'Taka', since she's used to calling him 'Bro' (oniichan).
I believe that this is what stymies Kana's ability to see her love for Taka
as anything worthwhile, because she's trapped into thinking of herself as
Taka's weak little sister.
- Conversely, though, it's perfectly normal to address a younger sibling
without using an affix. It's a sign of your relative (pun unintentional)
status in the family.
- Suggested CD tracks:
'Our Album' for Kana's monologue.
'The Tree on the Street at Sunset' for the scene in the park.
And 'The White Season', starting when It dawns on her, slowly.
Yes, there are continuity gaps in the game. As the game starts, Taka tells us that he has a little sister who's eighteen years old. Kana has just applied to get into Futaba High School, and was successful.
However, later in the game, when the flashbacks have ended and we've caught up with the present once more, Kana has just turned sixteen when she tries to get into high school. Taka gave her an electric mouse doll / a love candle / a big dictionary for her sixteenth birthday.
I assume that the change in Kana's age at the start of the game was made by G-Collections, firmly asserting the 'morality' of the game's storyline and the legality of Kana's involvement in scenes with sexual content. Noble though this is, I've chosen to go with the original scenario: that Kana is sixteen when her six-month deadline comes up.