I definitely see improvement when comparing part one to part 2, which is obviously good. Only a couple comments/typos.
-You used the word "I" 72 times in total, so you should try to cut those down a bit. A good idea is to just write the part with whatever words comes to mind, and then go back and re-write sentences that could be written to not use "I", if that makes any sense.
"I was thinking that, maybe I'll spend those two months preparing for our wedding." too much information came from my mouth, so I'll try to change the topic "by the way Hisao, I've thought of a date for our wedding to be on. It should be on our fifth anniversary."
-Is 2011 really 5 years after they met? Personally, I can't remember, but you may want to double-check this. I also could just be mis-understanding the current date.
We kissed for I don't know how long until we break up the kiss.
-This is a good example of when you should "Show" not "Tell". I'm thinking this up on the spot, but this would be more "Telling"--- "We kissed for what seemed like an eternity, until Hisao and I pulled away from each other's lips."
I think that kiss lasted for about fifteen seconds,
-If you wrote something about how long the kiss lasted before, you don't really need to mention it again.
"Correction. I'm your nerd." he says, he's got a point with that one though.
-Start a new sentence after "he says"-----"I'm your nerd", he says. He's got a point with that one though.
I pat his shoulder and point to the door, where his parents are visibly seen watching us for about half an hour at the front of the door. They must be enjoying our teasing a lot, considering they never bothered telling us how long we've been in front of the door. "Oh right, It's about dinnertime. We should head inside now, so we could help Mom with setting up the table." Hisao says, facing me with a sheepish smile on his face. Damn his smile, I always tend to blush every time I see that innocent smile on his face, it doesn't look forced, and looks great on his face. He should do that more often, we should stall time more often too.
-This is a very good paragraph. There is a nice balance of word choice and dialog, and things feel natural.
All of this teasing is kind of making me hungry, what's for dinner anyway? I take a look at what Mom made for dinner, and I am definitely bemused at what I see.
-This sentence feels awkward, mainly from the word "bemused". I like that you're using different word choice, but this feels out of place.
Mom calls us all as Hisao and Dad makes their way to the dining table, where we prayed before continuing to devour the meal Mom made for us.
-I'm not exactly caught up with Japanese culture, but I'm not really sure whether or not Hisao's family is Christian or not. In my opinion it's best to avoid religion like this in writing, unless what you're writing is all about religion. It just makes things complicated, and a little confusing at times.
"I'm just kidding, I'll say it again, Good night Hanako!" said Hisao, before kissing me while I'm still surprised from the pain on my forehead. "Feeling better now?" he says while smiling at me, which i answer with only a humming sound and hug, before continuing to go to my room and closed the door, before resting on the bed.
-Are Hisao and Hanako both sharing a room, or is it specifically Hanako's room?
Overall, you've shown significant improvement over short time, and I'm impressed. There are still some random typos that I didn't point out, like not capitalizing certain words, grammar, etc. Once again, I'd be happy to proof-read your work before you post it on here. By doing so, you will have less spelling mistakes, and grammar issues. A lot of writing teachers/professors say this, but reading your story out-loud to yourself helps a lot. This helps not only typos, but also helps you see if sentences make sense.