Living out of Tokyo (80 kms, in Odawara), around the corner from the hot springs (onsen) of Hakone, every day seems like the weekend (exaggerated grimace emoji).
City friends drool “I love Hakone, I planned to go last year, but couldn’t find time”.
TBH, going to Tokyo on a non-work day feels the same to me.
Most weekends I head to onsen in Hakone or even further afield.

Here are my onsen secrets, not far from Tokyo, on “my side of the mountain”.

Odakyu (Odawara) line from Shinjuku:
Atsugi: 七沢 (Nanasawa). One hour from Shinjuku, then a bus. Feels like real countryside.
Hadano area (easy to visit 大山 (Oyama) from Isehara for sight-seeing to make a day trip):
Tsurumaki-onsen: For a one-day visit (日帰り) Kobo-no-sato-yu (弘法の里湯) is most convenient.
Tokaidaigaku-mae station: Sazanka-no-yu is a short walk uphill from the station

Hakone: So many options, but my hot tip in the area is 姥子温泉 秀明館 (Uba-ko-onsen Shumeikan). It’s a world away. Stay all day, but bring a lunch-box.
天山 (Tenzan) is the only onsen I know that is OK with tattoos. The restaurants and sleeping room (over looking a river) are great, and many seasonal “events” (fireflies, etc.)
A nifty trip is to catch Daiyuzan line from Odawara 21 minutes to the last station, bus up to Saijo-ji temple (Daiyuzan) then hike across the mountain Myojo-ga-dake to 宮城野 (Miyagino) (near Hakone). After the hike, you’ll appreciate the hot springs here either the town onsen (町営) (cheap & cheery) or 勘太郎の湯 (Kantaro-no-yu).

Down the Izu peninsula, Yugawara is great. It was a getaway for samurai from Edo.
There are a few onsen, but my favourite is 嵯峨沢の湯 (Sagasawa-no-yu). It’s a hike up hill, or get the bus.
An incredible onsen is just south of Atami at 平鶴 (Hira-tsuru) Hotel, on the coast. The outdoor bath is virtually on the sea.

Up in the mountains, easier with a car, is 紅富士の湯 (Benifuji-no-yu) at Yamanaka-ko. Good view of Mt Fuji from the bath.
Another hot-spot (insanely inexpensive) is あしがら温泉 (Ashigara-onsen) which is operated by the town of 小山町 (Oyama-cho). This has one of the best views of Mt Fuji from a bath. It’s not far from Gotemba.

What’s your secret weekend getaway?