Hidamari Sketch/Ho Yay

Given the length of this list, are you really surprised to see Ume-sensei is a Yuri Fangirl?

Sae X Hiro
In General: There's so much of it that the pairing may be as much as official. "Sae: (smiling) You and I will always be together, so we'll never feel down. Hiro: (full blush) Sae... so you can say such things so naturally after all..."
 * When visiting a bath house, Sae and Hiro both eye each other uncomfortably while undressing. Miya breaks the tension with nudity.
 * Hiro, as it is pointed out numerous times in series, acts quite a good deal like Sae's wife.
 * See the picture at Engaging Conversation.
 * Yuno came into Sae's room to ask for School Festival ideas and was greeted with a Not What It Looks Like moment between Sae and Hiro first. After that incident cleared up, Sae picked up a picture of lilies as an example of what she drawn last year. The content of this went up by exponential levels in the anime.
 * Sae using a Lap Pillow moment between her and Hiro in her romance novel and upon Miyako reading it and blabbing about it, Hiro blushes and Sae gets extremely flustered.
 * At the Christmas party the Four-Girl Ensemble exchanged gifts, Sae got Hiro's--a ring--and after a little trouble found it fit perfectly on her ring finger. Sae immediately blushed at how misleading this might be, and Hiro told her (or perhaps just thought to herself) it was okay if she didn't wear it on her left hand.
 * Not to mention Sae's reaction when Hiro gets a love letter.
 * Some scenes in the second season OP have elements of this, including Intertwined Fingers.
 * This page from 2009-06:

"Sae: (blush) I think you're like a sugar candy..."
 * In episode 3 of the third season, we see Hiro sleeping. She smiles, stirs a bit and whispers: "Hhhmmmmmm... Saeeeeee..."
 * Or Sae's opinion on Hiro when they moved in...

"Nori: [The couple] didn't talk about anything special, but it was so touching..."
 * In Hoshimittsu episode 7, Sae and Hiro realize that they didn't really talk about much on a boat ride they took, just passing the time with casual conversation. Nori and Nazuna both are struck by how romantic this is, Nori declaring that it's like one of Sae's stories.


 * The Eyecatch immediately after this scene prominently features a white lily. Because it clearly wasn't obvious enough yet.
 * In a manga chapter Hiro has serious doubts about her motivation for becoming a teacher (and fear over losing touch with Sae and everyone at Hidamari.) Sae reassures her, telling her she'd be perfect for the job. Hiro shares her new found conviction with Yoshinoya, telling her "Someone who knows me better than I know myself gave me a push."
 * To further this, the next chapter shows Hiro has dozens of sketches of Sae sleeping.
 * In the first SP special, Hiro and Sae have such a powerful aura of closeness while standing together in a museum that people begin to back away.
 * The eye-catch afterwards shows Natsume with a hilarious "There is a great disturbance in the Force," expression.

Miyako X Yuno
"Miyako: Do you take me to be your wife? Yuno: I do! (Nori sweatdrops)"
 * A strip titled Because we're such close friends has Yuno wanting to joining in Nori and Nazuna's Skinship Grope of Miyako, but backs off due to embarrassment.
 * Of course, that's because Miyako loves to hop into the tub with Yuno.
 * Let's not forget Miya's "Yuno's pink panties are good too." line after jumping from the balcony to the lawn.
 * In episode 4 of Hoshimittsu, Miyako and Yuno play around with lace curtains and pretend to be brides.


 * Interestingly, Yuno X Miyako is the name of one particular strip where Miyako tries wearing Yuno's X-shaped hairclips. The result is... Yuno calling Miyako "Miyacchi."

Nori X Nazuna
The new tenants Nori and Nazuna also have their moments...
 * At the end of the 4th episode of Hoshimittsu, Nori invites Nazuna to the school's cafeteria while holding her hands, calling the invite "a date" and finally with Hiro's heart-pattern curtains in the background.
 * They end up holding hands a lot in various circumstances later on.
 * When Nazuna is suffering from home sickness Nori invites herself to sleep over.

Others

 * In the third season there appears to be immediate chemistry between Yuno and her sempai Arisawa.
 * Natsume has a pretty blatant crush on Sae.
 * There is some subtle byplay in this direction between Yoshinoya and Kuwahara as well, though the more obvious chemistry each has with the Principal may make that relationship more fitting for a different trope.
 * A scene by scene analysis can be found here