Now Gintoki doesn't just have parallels with Tsukuyo. In fact, a lot of the cast in Gintama have certain things that Gintoki can relate to. The biggest examples I can think of would be Hijikata, Jirocho, and Zenzo (Zenzo’s role in the SA arc was meant to mirror Gintoki's flashback in the same arc). However out of all of them I’d say Tsukuyo becomes the one who not only mirrors but also contrast Gintoki's character in the most ways.
Here's what they both have in common:
- Their clothing are very similar in design. http://imgur.com/a/fDyIL
- Gintoki wears a black shirt underneath his yukata which he only wears the left sleeve while the right one is left dangling beneath his obi. Tsukuyo wears a Kimono that only has one sleeve on her left arm. (Interestingly Tsukuyo’s black right arm cloth covers the part of her arm that Gintoki’s shirt doesn’t cover)
- Their kimono and yukata exposes their right leg.
- Gintoki's yukata has blue swirls covering the lower side of the sleeves and the area beneath his obi. Tsukuyo’s kimono is decorated with yellow autumn leaves on her sleeve and the area beneath her obi.
- Both of them have a blue obi in the manga (well Tsukuyo’s is more a very light shade of purple), and Gintoki has small lines of red on his shirt while Tsukuyo has a red belt. (the anime gave Tsukuyo a red obi and a blue belt instead).
- They both wear knee high black boots.
- Additionally Tsukuyo came wearing a jacket over her swim suit when she appeared during the pool episode, just like Gintoki was wearing that episode and many episodes before that.
- Their masters both “died” when they were teens.
- Both Shouyo and Jiraia raise their students so that one day they might be able to end their master.
- Shouyo and Jiraia were the names that their students called them, but these were not their real names (Yoshida Shouyo’s real name was Utsuro. Jiraia’s real name was Danzo)
- Jiraia and Shouyo “died” so that their students could live on. (Jiraia saving Tsukuyo from the falling debris when Yoshiwara was on fire, and Gintoki killing Shouyo to save himself and his friends)
- Their masters reappear again after their supposed death in front of their students. Shouyo re appears as the leader of the Naraku, Utsuro, and wears a mask and a hat. Jiraia re appears as the leader of the Red Spiders, and wears a mask that covers his face and hair. The members of both the Red Spiders and the Naraku have a tatoo to signify their membership. For the Naraku they have a tatoo of a Yatagarasu (which the wiki doesn't say anything about regarding their members, but Kondo could tell that their jailors were members of the Naraku from the Yatagarasu tatoo on one of their arms in the FS arc. Also Nobume has one.) The Red Spiders had a tattoo of a red spider.
- Gintoki killed Shoyo so that he could save Zura and Takasugi. Tsukuyo killed Jiraia to save Gintoki.
- In Tsukuyo's flashback we learn that Tsukuyo was constantly disobeying her superior and would get physically abused and locked in a room. Hinowa comes and she talks to her. Tsukuyo says that she doesn't care if she dies. Hinowa then talks about stuff and Tsukuyo receives food from her. After this Tsukuyo swears to protect her. Gintoki eventually wound up in prison after the end of the war and was eventually going to face excecution. He would sometimes get beaten by the executioners, and he also didn't care that he would die. But he was let free and wound up at a graveyard where he was given food from Otose. After this he swore to protect her.
- They both end up living with the woman they swore to protect and a child.
- They both lived their childhood without parents.
- This is what Hinowa says about Tsukuyo: "She always tries to bear the burden alone. I’m always so worried. Protecting me and Yoshiwara for so long, when she’s only a woman… Yet she never tries to rely on other people when something happens. She’s so focused on protecting others that she doesn’t allow others to protect her. But it’s different with you people. When she’s with you, she’s able to relax. Able to face you on equal footing and ask for help or offer help. You people are a true marvel… Any heavy burden, any attempt to shun others feels stupid when we’re around you."
- And this is what Otose says about Gintoki: "Always seemed as though he were looking for something. Butting in where he wasn’t wanted and pitting his own body to protect the things that were important for other people. Almost like he was trying to atone for something. Meanwhile, he kept nothing for himself. Didn’t get close to anyone. He was always alone…But you know… There were other strays who were drawn to that idiot. Soon he could no longer stay alone. Maybe he just learned from them. That fatalism won’t make anyone happy. That’s life. Rough, isn’t it? But you know, when I see the expressions on those three faces, I start to feel that it’s not too bad."
- This is what Jiraia says to Tsukuyo: "You may not be the sun that shines above the people but I alone know of your lunar beauty which secretly illuminates this land."
And this is what Tama says to Gintoki during Kintama arc: "True, your luster may not have been as bright as gold. Still, you were brighter than the fake glint of golden plating. Your silver was much more beautiful."
- When Gintoki's friends all prank him because he can't control himself when he's drunk and wrecked all the bars they went to during the scandal arc, Tsukuyo comments that he's a bad drinker. Sachan then calls her out on her hypocrisy and how she helped him wreck all the bars they visit. (Which makes you wonder why they didn't prank her too.) But even so. I really don't think I have to point out how bad she is when she’s drunk.
- They share some similarities with Umibozu and Kouka in terms of relationship and character. For example during Umibozu’s first meeting with Kouka he says "How about instead of suppressing these Orochi, you suppress the Orochi in my pants.” Gintoki's first words to Tsukuyo was “I thought those kunais were taking a stroll. How about it. Instead of these dangerous things. How about I use something better to stab you with.” Furthermore Kouka’s dress has the same high slit as Tsukuyo’s kimono, they both smoke a kiseru, they both have a somewhat stoic nature, and finally they both hit their love interest when they say something stupid(In Kouka's case she would shoot Umibozu during many of his attempts to flirt. And Tsukuyo loves throwing kunais at Gintoki) I guess another parallel would be how Kouka was refined to the Yato home planet and was finally able to explore the worlds outside thanks to Umibozu, while Tsukuyo could visit the world above Yoshiwara after Gintoki freed Yoshiwara from Hosen.
The stuff that contrasts with each other
- When Tsukuyo meets a new person she's super nice to them. When Gintoki meets someone for the first time he more often than not won’t start off on a friendly note.
- Gintoki is lazy by nature while Tsukuyo works way harder than she needs to.
- Gintoki wears a white yukata. Tsukuyo wears a black kimono.
- While Utsuro has been referred to as someone who watches from above with him being a member of the Tendoshu and Naraku. Unless you guys haven't noticed, there's been a lot of instances where Utsuro is watching from above (like during most of the Rakuyou arc, some of the FS arc, and recently in the silver soul arc where he was watching from above as the people from Edo defended Kabukicho). Meanwhile Jiraia was always a spider on the ground that in Gintoki's words "a lone spider spinning his web while looking longingly at the moon)
During one of the Gintaman episodes they were talking about ways to make the manga more interesting. One thing they discussed was about giving the main character a love interest, and Gintoki listed a bunch of traits.
- She must be sexy with big boobs.
- Her dream is to become the main character’s bride. (Probably not Tsukyo's dream. But she did get pretty sad and jealous when she heard that Gintoki got “married” with Sachan during one of the New Year episode.)
- She must speak with an accent.
- She has 48 sisters (In that case, can you carry everybody here? Your mothers... All 49 of them. - Tsukuyo to Seita during the Yoshiwara in flames arc when he tries to carry Hinowa to safety)
- She can’t hold her liquor.
And in this episode, the main character of Gintaman, Ginto, confesses his feelings to his love interest. However it's important to note that this episode was filler.
Now here's a theory that might be a pretty far fetched one about Gintoki's feelings towards Tsukuyo.
I think Gintoki deep down loves Tsukuyo. Obviously he thinks she's beautiful and hot. (You can see this in Yoshiwara in flames when he tries to flirt with her. The bathhouse episode where he admires her tits and ass. And how he thinks her face and soul is beautiful at the end of the Red Spider arc.)
I think he fell in love with her after she could do what he himself never could. She was able to shoulder her teacher’s burden. So why isn't he flirting with her or is generally more apparent of his emotions if he really is in love? Well remember how in the Mitsuba arc Hijikata never wanted to be close to Mitsuba because he didn't think he could give her the happiness she deserves? I think it's something similar with Gintoki and Tsukuyo. Remember how Gintoki called Jiraia a coward and that Tsukuyo was far stronger than he could ever be? Gintoki told Jiraia afterwards that a coward is enough to fight another coward, so I think the same thing applies here. Gintoki thinks that a coward like himself shouldn't be with someone as strong as Tsukuyo, and because of this he's running away from these feelings like he did in the past. He's not one who initiates friendships. Like he said to Kamui. They all made their way into his heart on their own before he knew it. All he has done is help the ones in need, and they then seek out Gintoki's company on their own. He’ll just keep on with his crush on Ketsuno Ana while Tsukuyo is out of the question. He hasn't accepted these feelings, so the love that he has always had is the love he has towards everyone and treating them equally (like how the love incense showed the extreme of that, and then Tsukuyo’s words to Hotaru). When it comes to the effect of the incense on Tsukuyo, it brought out the extreme of her conflicting, tsundere love for Gintoki. The effect on Gintoki, like I said brought out the extreme of his love for everyone. But I also think it brought out some of the feelings that he hid inside himself, and it surfaced when he told Tsukuyo that if she wants to, he’ll be hers, and when he then said he was joking and told her he can't’ seem to talk to the woman he really wants to be with like he does to the others. (Maybe even suggesting how his feelings towards Ketsuno Ana differs from Tsukuyo) He plays it off by hiding it again like he always does. Like I said. It's far fetched.
Another interesting thing is that there's a part in the Gintoki vs Hosen fight where Hosen is holding a tight grip on Gintoki’s head and has him pinned against the wall. Hosen taunts him about a few things, but the main one is women. He goes on about how the samurai lost the right to their women when they couldn't even defend against the Amanto. When you lose your den, you must surrender your women too. Finally he taunts him about how a loser like him should just watch as his country and women are violated by the strong. Then when Hosen is about to kill him, Gintoki stabs Hosen’s eye with Tsukuyo's kiseru. Maybe it's a hint to who Gintoki's woman might be.
Now I can imagine the biggest question regarding all of this is. "Okay. Even if all of this is true and it's building up for either a final pairing or some kind of scene together. Why would Sorachi put so much attention to this sub plot that doesn't have anything to do with the themes of Gintama?" My answer is... I honestly don't know. Maybe it's the final thing to round up Gintoki's character arc of letting himself enjoy life to the fullest. Or it might just be because he wants to do it for his own reasons.
Are some of these grasping for straws? Maybe. But I don't believe I'm completely delusional or that some of these might be coincidences. I don't think I've ever analyzed or theorized something as much as I've done with GinTsu. But the reason why is that I think they are compatible, cute, funny etc. together. Maybe they end up together, or maybe not. But what I want more than anything is to have a scene similar to where Gintoki helped Tsukuyo overcome her facing Jiraia, with Gintoki's dilemma with Utsuro. Both Jiraia and Utsuro were very eager for their existence to end. (Well Jiraia wanted it to happen in a specific way while way Utsuro is fine to end it by any means)
TL;DR: They have stuff in common and something is bound to happen eventually. Also please read the whole thing, I spent way too much time on it.