Honestly, it's not that hard to get a girl's good ending in KS. IMHO, the game does a fine job of emphasizing the keystones of healthy relationships. If you understand how relationships - and people - work and have a reasonable amount of empathy, the right choices are fairly obvious - they're the ones that don't involve acting like a moody, pretentious jerk.I really did want to have a good ending without consulting a flow chart
WARNING: Incoming wall of text!
Major spoilers, too.
Shizune: Communication. A relationship can't even begin unless you and your partner know each other's hearts, and that can only happen if you share what's on your minds. If something's bothering you, talk about it. If everything is right with the world, talk about it. If you're happy or sad or angry or scared, talk about it. You can't address problems if you don't know something's wrong, and a problem that isn't dealt with is a problem that will possibly fester and grow into a relationship-destroying catastrophe. Keep the lines of communication open to nip potential issues in the bud - and if there *are* no issues, just tell your SO how much you love them. That never hurts.
Also, don't cheat on your partner.
Case study: Misha is hiding her true feelings about her dysfunctional relationship with Shizune, both from Shizune and from herself. Hisao must help her release and address these feelings; they will gradually weaken and destroy the trio's relationships with each other if left buried.
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Lilly: Trust. Let your special someone into your heart, completely and totally. Don't hide things from them, even if you think it's for the best, because that undermines their ability to trust you. Be honest about your feelings at all times.
Case study: Lilly is blind. She cannot percieve that which would be obvious to most others - and thus has great potential to be mislead and lied to. Hisao must tell her his feelings and not lie to her - even when it would be really easy to get away with - in order to build and keep her trust in him.
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Rin: Understanding. Learn how to listen to your special someone - both directly, and through their less overt cues. Understand what it is that they really want, even if you don't understand the how or why of their actions, and help them find their path to happiness.
Case study: Rin is...odd. Although her behavior as an individual may be off-kilter, her feelings are not - her basic motivations are no different from the rest of us despite her unusual quirks. Hisao must learn to see past her erratic surface behavior and understand what truly drives her - even if Rin herself doesn't know for certain.
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Hanako: Respect. Your partner is not your pet. Don't presume things on their account. Don't act *for* a person; act *with* them. Respect their choices, and don't attempt to interfere based on what you think 'should' be. Let them take the lead in their own affairs, but be willing to step in and selflessly offer help if and when they ask for it. Know the difference between being someone's crutch, and being there to help them up when they fall.
Case study: Hanako has an inferiority complex. While the reflexive urge to assuage her fears and coddle her is understandable, this is not what she needs, nor what she wants. Hisao must realize that only Hanako knows what's best for Hanako - that the best way to help Hanako, is to help her help herself.
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Emi: Determination. There *will* be bumps in the road along the way, and that's 100% normal. Don't blow things out of proportion; accept that conflict will arise, and do what it takes to resolve it. Make compromises if you need to. Don't give up; put forth the effort to fight for a good thing.
Case study: Emi is emotionally distant - deep down, she *wants* to love, but her fear of loss keeps causing her to subconciously push others away. She cannot seem to stop this on her own, so Hisao must compensate by simply refusing to *be* pushed away - to stand there and weather the storm, until Emi is ready to accept both his presence and her own feelings.
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Manly Picnic: Responsiveness.Kind of a no-brainer, but it still needs to be said. Love doesn't just happen - you do have to make the effort. Relationships don't just fall into your lap - you have to recognize the opportunity and act to sieze it. Is there a guy or girl you like? Tell them - ask them out on a date. Is there someone who's been spending time with you - making the effort to get to know you, perhaps hinting at something more? Don't sit there and wonder - ask them how they feel. Did a cute girl crash into you and almost give you a heart attack? It's the perfect icebreaker - take the opportunity to strike up a conversation. Under *no* circumstances play hard to get - make yourself available, and if someone takes the bait, do your damndest to reel them in.
Don't act all emo and wallow in self-pity - find something that makes you happy, and let that happiness infect others like a bad social disease. You don't have to be the most confident guy in the world to appeal to others - heck, some folks *prefer* shy types like us - but you *do* have to have a positive mindset. Nobody wants to be around a Gloomy Gus, because all they can see is the bad - the negative. Show the world your positive side - and if a bunch of cute girls try to drag you out of your shell, for God's sake, let them.
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As far as I can tell, all of the bad endings in KS ultimately result from being an insensitive, obstinate blockhead. If you really pay attention to the girls' feelings and have some common sense regarding relationships (see the above guidelines), the bad choices are usually fairly obvious.
...wow this turned into a bit of an essay, didn't it? Sorry, I tend to pontificate sometimes on matters that mean a lot to me, and matters of the heart are high on that list.