Ah, a post-molt Grea before she cut her hair...I'm all about that life. Dragon girls forever. Anne and Grea are very obviously into each-other. Anne may seem the thirstier of the two, but that is only because her general personality is more outgoing and open. Grea is shy and easily embarrassed (which only adds to her God-tier waifu status), which is why she finds it more difficult to express herself. However, probably the most telling scene in the whole anime is when Anne trips on the boat and lands on top of Grea. They are both locked in a romatically compromised position for a moment and neither seems to want to leave it until they both slowly withdraw, suddenly self-conscious. Last time I checked, people who are JUST friends don't behave that way. Just saying.
Saikawa being the way she is, I'm pretty sure learning that Kanna is a dragon from another world would only make her like her even more, if that's still possible :P
Funfact: Jupiter is actually only about middling size as gas giants go; the things can go up to about 13 times its mass before turning into brown dwarves (the specifics of the cutoff are subject to debate)
Funfact #2: due to gravitational compression the dimensions of gas giants stay very similar over quite wide mass ranges (eg. Jupiter and Saturn are close to the same radius - ca. 11.5 vs. 9.5 Earths at equator - despite the latter having only ~30% of the former's mass), though thermal expansion can disproportionately "puff up" "hot Jupiters" orbiting close to their stars
^ Yeah, hot jupiters that get too close and become very large but very low density are indeed known as puffy planets or puffy giants or super saturns (a nod to Saturn being the least dense planet in the solar system, at ~70% the density of water)