The sencha is still bitter at 70°C and I’m running out of things to blame

[Garden In Order]

Question or objective: more sweetness and less bitter edge
Tea category: Japanese green tea
Exact product: Spring Needle 2025 sencha
Vendor: North Window Tea
Origin: Shizuoka, Japan
Cultivar, if known: Yabukita
Harvest season/year: spring 2025
Processing or roast: light-steamed sencha
Cake/batch number, if relevant: cake/lot noted above where applicable; otherwise N/A
Purchase/opening date: purchased 2026-06-10; opened 2026-07-03
Storage since purchase: refrigerated sealed pouch; portion warmed before opening
Style: gongfu-ish kyusu
Vessel: Tokoname kyusu
Vessel material: unglazed clay
Nominal and actual filled capacity: 180 ml nominal / 150 ml filled
Filter or strainer: ceramic sasame
Kettle: standard electric kettle + thermometer
Vessel preheated: no
Dry leaf weight: 5.0 g
Water volume: 150 ml
Water temperature: 70°C
Water source or mineral profile: filtered tap water, London; moderately hard
Rinse: 5-10 s where noted by the recipe; otherwise none
Infusion schedule: 60 s, then 20 s, 35 s
Agitation: one gentle swirl before first pour
Was each infusion completely decanted?: yes
Aroma: fresh grass and nori
Sweetness: low
Bitterness: high
Astringency: medium
Body/texture: medium-light
Flavour: spinach, citrus peel
Aftertaste: dry and sharp
Number of satisfying infusions: 3
Exact problem: bitterness dominates before sweetness appears
Desired result: more sweetness and less bitter edge
Variable changed: temperature
Previous value: 75°C
New value: 70°C
Result: bitterness dropped slightly but the cup is still harsh
Dry-leaf photograph: available in the author’s notes; not embedded in this archive
Liquor photograph: available in the author’s notes; not embedded in this archive
Wet-leaf photograph: available in the author’s notes; not embedded in this archive
Video if pouring or drainage is relevant: not relevant

I have reached the stage where changing three things at once is only producing new kinds of confusion. The cup is giving me bitterness dominates before sweetness appears. The last controlled change was temperature: 75°C to 70°C, and bitterness dropped slightly but the cup is still harsh. I would like the next test to be one variable only. If you have brewed this exact tea, or something genuinely comparable in a similar vessel, that would be especially useful.

My target is simple: more sweetness and less bitter edge. I am not looking for a new shopping list unless the equipment is actually the problem.

[Garden In Order]

Tested solution
Direct recommendation: shorten first infusion to 40 seconds.
Applies to: Spring Needle 2025 sencha / Japanese green tea in a setup close to Tokoname kyusu.
Evidence: firsthand test by the questioner on Spring Needle 2025 sencha.
Change: shorten first infusion to 40 seconds.
Expected effect: less bitterness while preserving aroma.
Observed result: bitterness dropped slightly but the cup is still harsh.
Limitations: This may not transfer to a heavier roast or a very different vessel size.
Commercial relationship: none.

[Crowd Wok]

Same tea/batch
Direct recommendation: reduce leaf to 4.5 g.
Applies to: Spring Needle 2025 sencha / Japanese green tea in a setup close to Tokoname kyusu.
Evidence: firsthand use of the same Spring Needle 2025 sencha in a closely matched setup.
Change: reduce leaf to 4.5 g.
Expected effect: slightly lighter body with more room for sweetness.
Observed result: not tested on this exact setup yet.
Limitations: This may not transfer to a heavier roast or a very different vessel size.
Commercial relationship: none.

[Garden In Order]

Controlled test
Direct recommendation: shorten first infusion to 40 seconds.
Applies to: Spring Needle 2025 sencha / Japanese green tea in a setup close to Tokoname kyusu.
Evidence: side-by-side or repeated one-variable test.
Change: shorten first infusion to 40 seconds.
Expected effect: less bitterness while preserving aroma.
Observed result: not tested on this exact setup yet.
Limitations: My result is from a small number of sessions, so treat it as evidence rather than law.
Commercial relationship: none.

[Ringside And Rescue]

Same tea/batch
Direct recommendation: reduce leaf to 4.5 g.
Applies to: Spring Needle 2025 sencha / Japanese green tea in a setup close to Tokoname kyusu.
Evidence: firsthand use of the same Spring Needle 2025 sencha in a closely matched setup.
Change: reduce leaf to 4.5 g.
Expected effect: slightly lighter body with more room for sweetness.
Observed result: not tested on this exact setup yet.
Limitations: Water chemistry may change the result, so I would not generalize this to every city.
Commercial relationship: none.

[Ringside And Rescue]

Comparable tea
Direct recommendation: try softer water.
Applies to: Spring Needle 2025 sencha / Japanese green tea in a setup close to Tokoname kyusu.
Evidence: firsthand use of a comparable Japanese green tea with similar parameters.
Change: try softer water.
Expected effect: cleaner sweetness and more distinct umami.
Observed result: not tested on this exact setup yet.
Limitations: Water chemistry may change the result, so I would not generalize this to every city.
Commercial relationship: none.

[Ringside And Rescue]

Comparable tea
Direct recommendation: reduce leaf to 4.5 g.
Applies to: Spring Needle 2025 sencha / Japanese green tea in a setup close to Tokoname kyusu.
Evidence: firsthand experience with Japanese green tea in a different vessel.
Change: reduce leaf to 4.5 g.
Expected effect: slightly lighter body with more room for sweetness.
Observed result: not tested on this exact setup yet.
Limitations: If your actual filled volume differs from the stated volume, the ratio may be the bigger issue.
Commercial relationship: none.

[Garden In Order]

Professional experience
Direct recommendation: try softer water.
Applies to: Spring Needle 2025 sencha / Japanese green tea in a setup close to Tokoname kyusu.
Evidence: general brewing principle consistent with repeated tests; not this exact batch.
Change: try softer water.
Expected effect: cleaner sweetness and more distinct umami.
Observed result: not tested on this exact setup yet.
Limitations: If your actual filled volume differs from the stated volume, the ratio may be the bigger issue.
Commercial relationship: none.

[Crowd Wok]

Inference
Direct recommendation: shorten first infusion to 40 seconds.
Applies to: Spring Needle 2025 sencha / Japanese green tea in a setup close to Tokoname kyusu.
Evidence: inference from the posted parameters, not a test of this exact tea.
Change: shorten first infusion to 40 seconds.
Expected effect: less bitterness while preserving aroma.
Observed result: not tested on this exact setup yet.
Limitations: If your actual filled volume differs from the stated volume, the ratio may be the bigger issue.
Commercial relationship: none.

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